®IjE p. p. 1|iU pbrarg
^orti| Carolina ^tate College
griculture
>TR Y.
mjuiima vr
r
\ Purchased, \ Price,
Date Due
21240
U&e Kucal ^cimct Veriest
Edited by L. H. Bailey
IRRIGATION AND DRAINAGE
•'Tl]^><9>^o
IRRiaATION AND DRAINAGE
PRINCIPLES AND PRACTICE
OF THEIR
CULTURAL PHASES
F. H. KING
Professor of Agricultural Physics iu the University of Wisconsin;
Author of "The Soil"
THE MACMILLAN COMPANY
LONDON: MACMILLAN & CO., Ltd.
1899
All rights reserved
Copyright. 1899
By F. H. king
g^oimt IPIeasant gJtinterp
J. Horace McFarland Compar.y
Harrisbur^. Pa.
PREFACE
Most works on irrigatiou have been written
from the legal or sociological standpoint, or from
that of the engineer, rather than from the cul-
tural phases of the subject. The effort is made
here to present in a broad yet specific way the
fundamental principles which underlie the methods
of culture by irrigation and drainage. Distinc-
tively engineering principles and problems, as such,
have been avoided, and so have those of plant
husbandry. The aim has been to deal with those
relations of water to soils and to plants which
must be grasped in order to permit a rational
practice of applying, removing or conserving soil
moisture in crop production. The immediately
practical i)roblems, from the farmer's, fruit-grower's
and gardener's standpoints, with the principles
which underlie them, are presented in as con-
crete and concise a manner as appears needful
to build up a rational practice of irrigation
culture and farm drainage ; and the effort has
been to broaden the conceptions of general soil
(v)
21240
vi Preface
management, even when neither irrigation nor
drainage is practiced.
Great pains has been taken to personally
inspect the irrigation practices of both humid and
arid climates in this country and in Europe, to
gain a broader view of essential details, and to
secure suitable illustrations, which are presented
largely as photo -engravings, in the hope of getting
closer to the spirit of the subject.
Free use has been made of all available litera-
ture on the subject, and credit is given throughout
the body of the text to various writers and
works.
F. H. KING.
University of Wisconsin,
March, 1899.
CONTENTS
INTRODUCTION (pages 1-65)
General Remarks on the Importance of Water
PAGES
Definition of irrigation and drainage — Importance of water
in crop production — Plants adapted to intermittent
watering — Variation in the capacity of soils for water —
Adaptation of plants to soils of different water capacity
— Variations in soils and in rainfall may make irrigation
or drainage needful — Better aeration and deeper root
feeding in arid soils — Explanations not entirely satis-
factory 1-9
The Advantages of Abundant Supply of Soil Moisture. — Large
volumes of water generally needed — Part played by water
in crop production — Relation to plant life — Relation to
soil microbes — Rains and irrigation may start formation
of nitrates by diluting soil moisture — Relation of drain-
age to development of nitrates and soil fertility — Soil
water dissolves ash ingredients of plant -food — Water
causes oxygen, carbon dioxide and nitrogen to enter
the soil 9-15
Water only One of the Necessary Plant- foods. — Difference in
value of water for plant-food — More water used than
any other substance 15, 16
Amount of Water Used by Plants. — Relation of climate to
water used — Treatment of soil affects amount of water
used — Irrigation and drainage modify amount of soil
moisture — Apparatus used in measuring water used by
plants — Aims of the experiments — First trials with oats,
barley and maize — Field results with maize — Changes
of soil moisture in field — Experiments with oats and
barley — Experiments of 1893 to 1896 16 38
(vii)
viii Contents
PAGES
Variations in ill e Amount of Water Used by Plants. — Two
years compared — Field and plant-house yields compared
— Loss of water in a saturated air — Amount of water
required to produce one ton of dry matter 39-46
The Mechanism and Method of Transpiration in Plants. —
Transpiration and breathing — Structure of barley leaf —
Inevitable loss of water by evaporation makes demands
large — Amount of air breathed by clover to secure the
needed carbon — Changes in humidity of air over a clover
field — Assimilation of carbon takes place only in sun-
shine — Breathing pores in leaves — How stomata per-
mit and prevent loss of water — Structure of breathing
pores 4G-54:
Mechanism by ivhich Land Plants Supply Themselves icith
Water. — Part played by roots — Essential features of
roots — Only the newer portions active in absorbing
moisture — How water is taken xip — Eate of feeding
slows down as thickness of film becomes less — Eoot
hairs acid and may hasten solution of plant-food — Need
of great extent of root surface — Distribution of roots in
soil — How roots advan^-e throug'h soil — The root-cap. . . . 54-65
Part I
IRRIGATION CULTURE
CHAPTER I
The Extent and Geographic Range of Irrigation
(pages 66-90)
The Antiquity of Irrigation.— In Egypt — In Assyria — By
the Phoenicians — Early Grecian and Roman — In China
— In Mexico and Peru 66-72
Extent of Irrigation.— In the Po valley — In Sicily — In
Spain — In France — In Switzerland — In Belgium — In
Denmark — In Austria-Hungaria — In Bavaria — In Eng-
land — In India — In Ceylon — In Australia -In other
Cont€7its ix
PAGKS
parts of Asia — In Algeria — In Egypt — In Cape Colony
— In Madagascar — In the Hawaiian Islands — In Java —
In South America — In the Argentine Republic — In
Western United States — Amount of land irrigated 72-89
The Climatic Conditions Under ivltich Irrigation Has Been
Practiced. — Amount of rainfall where irrigation has been
practiced — Distribution of rain with reference to the
growing season 89, 90
CHAPTER II
The Conditions which Make Irrigation Imperative,
Desirable, or Unnecessary (pages 91-116)
Objects of Irrigation. — To establish right moisture relations
— To increase fertility — To change texture of soil — To
build up low areas — For sewage disposal 91-94 '
The Least Amount of Water tohich Can Produce a Paying
Crop. — Importance of the subject — Amount of water
needed for wheat — Slow rate of evaporation from dry
soil — Average yield of wheat as related to rainfall —
Dry farming 95-101
Like Amounts of Eainfall not EqualJii Productive. — Differ-
ences in yield and in rainfall — Causes of differences . . 101-106
Frequency and Length of Periods of Drought — Abundant
watering at short intervals needful— Type of rain dis-
tribution-Ineffective rains — Length of rainfall periods
in Wisconsin — Yield of crops compared with rainfall —
Length of too long periods of no rain — Yields due to
rainfall and to irrigation compared 106-110
Conditions which Modify the Effectivetiess of RainfaU. — In-
-fluence of soil texture — Amount of moisture in soil
when growth is checked — Loss of water by percolation
— Rapid percolation chief cause of poor yields — Supple-
mentary irrigation helpful on light lands— Topographic
conditions influencing effectiveness — Sub-irrigation may
supplement rainfall 110-116
X Contents
CHAPTER III
The Extent to which Tillage May Take the Place
OF Irrigation (pages 117-170)
PAGES
TJie Insufficiency of Water to Irrigate all Cultivated Lands. —
Discharge of the Mississippi river — Mean annual run-
off for the United States — Proportion of cultivated
fields which might l>e irrigated 117-120
Most loliich may he Hoped for Tillage in the Use of Water. —
Do soils take moisture from air to helpful extent ? —
Tillage does not diminish transpiration in plants, and
cannot dispense with water 120, 121
Tlie Amount of Bain Needed to Produce Maximum Crops in
Humid and Sui -humid Ecgions. — Acre -inches required
for a pound of dry matter — The amount of available
rainfall in the United States — Effective rainfall of 13
states — Theoretical yields which may be expected 121-125
The Distribution of Bain in Time Unfavorable to Maximum
Yields. — Mean yields of bai'ley, oats and maize in 18
states — Small mean yields, due to unfavorable dis-
tribution of rain 125-127
Methods of Tillage to Conserve Moisture often Ineffective. —
Cultivation inapplicable — Meadows and pastures — Mean
yield of hay in 13 states — Relation of yield of hay to
eifective rainfall — Tillage methods only partly appli-
cable to small grains 127, 128
Tillage to Save Moisture is Chiefly Effective in Saving Winter
and Early Spring Bains. — Late rains largely absorbed
by the surface three inches — Roots develop close to
the surface in late summer 128,129
Midsummer and Early Fall Crops Difficult to Eaise without
Irrigation. — Summer rains less effective— Yields of sec-
ond crop clover — A crop of barley and hay the same
season 129-131
Contents xi
PAGES
Fall Plowing to Conserve Moisture. — How most effective —
Amount of moisture saved — Most important in sub-
humid climates — Applicable to orchards and small
fruits 131-133
SubsoiUng to Conserve Moisture. — Magnitude of the effects
—Duration of the effects 133-138
Explanation of Effects of SubsoiUng. — Increases water ca-
pacity of soil stirred — Decreases the capillary conduct-
ing power — Allows the water to enter soil more deeply
— Larger per cent of water available to crops 139-142
Earth Mulches. — Conditions modifying effectiveness — Loses
in effectiveness with age — Other mulches — Too close
pasturing wasteful — Value of surface dressings of ma-
nure—Harrowing and rolling small grains after they
are up 142-147
Early Tillage to Save Moisture. — Amount saved — Most
effective tools — Early stirring rather than early
planting 147-151
Danger of Ploicing Under Green Manures. — Catch crops in
humid and sub-humid climates 151-153
Summer Fallowing in Relation to Soil Moisture 153,154
Influence of Summer Fallowing on Soil Moisture and on
Plant-food 154-157
Old Systems of Intertillage. — Jethro Tull's method —
Hunter's modification — The Lois-Weedon system —
Planting and tillage to utilize the whole rainfall —
Distance roots of corn and potatoes spread laterally —
Distribution of moisture in potato field — Lateral feed-
ing of oats — Horse-hoeing grain a form of summer
fallowing 157-163
Frequency of Tillage to Conserve Soil Moisture. — Should
often take place at the earliest possible moment — Dan-
ger from late tillage 164,165
xii Contents
PAGES
Jlie Proper Depth of Surface Tillage and Eklged and Flat
Cultivation. — Depth of early tillage — Deep ridges objec-
tionable — Eidge cultivation may be advisable for potato
culture 165,166
Boiling in Relation to Soil Moisture. — Firming the surface
to establish capillary connection with the soil below —
Rolling may warm soil — Rolling may bring water to the
surface — The press drill 166,167
Destructive Effects of Wi>ids. — Conditions for injury — De-
structive effects on sandy lands — Influence of groves
and hedgerows on evaporation — Protective influence of
grass — The value of hedges in windy sections 168-170
CHAPTER IV
The Increase of Yield Due to Irrigation in Humid Climates
(pages 171-195)
Importance of the Amount and Distribution of Water in
Potato Culture, and the Advantage of Irrigation in Cli-
mates like Wisconsin. — Time and method of planting-
Amount of water used — Differences in yield 171-175
Effect of Supplementing the Bainfall in Wisconsin for Cab-
bage Culture.— Method, of planting — Weight of heads-
Influence on yield of thick and thin planting — Amount
of water given crop 175, 176
Eff'ect of Supplementing the Bainfall xvith Irrigation on the
Yield of Corn. — Difference in yield and in water used. . 176-178
Effect of Supplementing the Bainfall with Irrigation on the
Yield of Clover and Hay 178,179
A Crop of Barley and a Crop of Hay the Same Season 179-181
Effect of Supplementing the Bainfall for StroM-berries 181
Contents xiii
PAGES
Closer Planting Made Possible bij Irrigation. — Breathing
room in the soil limited — Soil temperature lowered by
close planting — Amount of sunshine limited — Ten-
dency to lodge when planted too close — Possible insuf-
ficiency of carbon dioxide — Amount of carbon used by
maize 181-187
TJie Maximum Limit of Productiveness for Maise. — Mean
weight of plants — Maximum yields computed — Observed
yields 187-190
Observed Yields of Maize per acre, Planted in Different
Degrees of Thickness and loith Di^erent Amounts of
Water. — Yields of dry matter— Yields of shelled corn. . 190-193
Influence of Thick Seeding and Irrigation on the Develop-
ment of the Plant. — Lengthening of the nodes 193-195
CHAPTER V
Amount and Measurement of Water for Irrigation
(pages 196-221)
The Maximum Duty of Water in Crop Production 196-199
Conditions which Modify the Amount of Water Required far
Irrigation. — Peculiarities of crop — Character of soil —
Character of subsoil — Character of rainfall — Frequency
and thoroughness of cultivation — Closeness of planting
— Fertility of land — Frequency of applying water 199-208
Amount of Water Used in Irrigation. — In Italy — In Spain
and France — In Egypt — General tables — Mean amount
— For sugar cane — Highest probable duty, table —
Bushels of grain per cubic foot of water, table 208-217
Duty of Water in Bice Culture 217,218
Duty of Water on Water-meadows 219,220
Duty of Water in Cranberry Culture 220,221
xiv Contents
CHAPTER VI
Frequency, Amount and Measurement of "Water for Single
Irrigations (page 222-247)
PAGES
Amount of Water for Single Irrigations. — Soil leaching in
humid climates — Conditions which determine the
amount of water used — Conditions which determine the
frequency of irrigation 222-224
Capacity of Soils to Store Water under Field Conditions. —
Amount of soil moisture when growth was cheeked —
Upper and lower limits of best amount — Amount
needed for one irrigation 224-227
Depth of Root Penetration. — Prune on Peach — Apple —
Grape— Raspberry— Strawberry— Alfalfa 227-234
Frequency of Jrn"^«?(o?i.— Theoretical— For wheat— For
maize — For clover, alfalfa and meadows — For potatoes
—For rice 234-239
Measurement of Water. — Necessity — Advantages 239
Units of Measurement. — Acre-inch — Acre-foot — Second-
foot— Miner's inch 239-241
Methods of Measurement . — Time division — Subdivision of
laterals — Use of divisors — Use of modules 241-247
CHAPTER VII
Character of Water for Irrigation (pages 248-268)
Temperature of Water for Irrigation. — Best temperature —
Danger from cold water — Amount soil temperature may
be lowered 248-251
Fertilizing Value of Irrigation Water. — Amount in two acre -
feet 251-253
Sewage Water for Irrigation. — On Craigentinny meadows —
Healthfulness of milk from sewage grass 253-258
Contents xv
PAGES
TJie Value of Turbid Water in Irrigation. — Eio Grande —
Po— Nile— Durance 259, 260
Improvement of Land by Silting. — Warping or colmatage—
Silting of gravelly soils ._ 261-264
Opportunities for Silting in Eastern United States. — In Wis-
consin and Michigan — In New York and New Jersey —
In the South 264-266
Alkali Waters not Suitable for Irrigation. — Safe and unsafe
alkali waters 266-268
CHAPTER VIII
Alkali Lands (pages 269-289)
Characteristics of Alkali Lands 269, 270
Causes of Injuries by Alkalies. — Plasmolytie effects — Toxic
effects 270, 271
Hoiv Alkalies Accumulate in the Soil. — By capillarity — In
marsh soils by underflow 272-274
Intensive Farming may Tend to the Accumtdation of Alkalies. 274, 275
Amount of Soluble Salts which are Injurious in Soils. — Con-
clusions of Plagniol — Of Deh^rain — Of Gasparin — Of
Hilgard— Plasmolytie action 275-278
Composition of Alkali Salts. — In California— In Washington . 278-280
Appearance of Vegetation on Alkali Lands. — In arid regions —
In humid regions 281-283
Conditions which Modify the Distribution of Alkalies in Soil.
—Tillage— Shading— Action of roots 283, 284
Use of Land Plaster to Destroy Black Alkali. — Hilgard's
conclusions , 284, 285
Kinds of Soil ivhich Soonest Develop Alkali 286
Correction of Alkali Water before Use in Irrigation 287
Drainage Must be Ultimate Remedy for Alkali Lands 287-289
xvi Contents
CHAPTER IX
Supplying Water for Irrigation (pages 290-328)
PAGES
Diverting River Waters. — Sirhind canal — Kern Island canal —
Dangers from seepage — Redlauds system — Redwood
pipe line — Invei'ted siphon — Redwood flume — Cement
flume — Cement hydrants 290 304
Diverting Underground Waters. — By submerged dams — By
submerged canals — By tunnels 304, 305
Diverting Water hy Tidal Damming 306
Diverting Water by Power of the Stream. — Undershot wheels
— Bucket wheels — Turbines — Hydraulic rams — Ram-
ming engines— Siphon elevator 306-310
Utilizing Storm Waters for Drigation 311, 312
Wind Power for Irrigation. — Record of experiments 312-316
Water Pumped in 10-day Periods. — Number of acres a
windmill may irrigate 316-318
Necessary Conditions for the Highest Service with a Wind-
mill. — Good exposure— More than one pump — Storage
system 318, 319
The Use of Reservoirs. — Construction— Size to supply given
areas 320-323
Pumping Water with Engines.— Cost with gasolene— With
steam— In Egypt 324 327
Use of Animal Power for Lifting Water for Irrigation. —
Persian wheel — Bucket pump— Doon- Shadoof 328
CHAPTER X
Methods of Applying Water in Irrigation (pages 329-402)
Principles Governing the Wetting of Soils. — Influence of
texture — Effect of soil becoming dry 330-334
Contents xvii
PAGES
Principles Governing the Puddling of Soils. — Character of
puddling — Bad effects — Precautions to prevent 334-336
Principles Governing the Washing of Soils. — Tlie common
mistake — What constitutes good irrigation — Methods
which prevent washing 337^ 338
Field Irrigation by Flooding. — Two different types — Used
most where intertillage cannot be practiced — Flooding
by running water — As practiced in Colorado — Where
slopes are steep — Where fields are short — Flooding by
cheeks — Size of checks — Forming cheeks — On irregular
slopes — Handling the water — Large systems - Forming
check ridges 338-350
Fitting the Surface for Irrigation. — Leveling devices —
Shuart land grader — French land grader 351, 352
Field Irrigation by i^Mrroics.— Adapted to intertillage crops
— Watering before planting — Irrigation of potatoes —
Watering alternate rows — Lateral spreading of water —
Effect on yield— Watering sugar beets and maize 352-359
Water -meadoios. — Laid out for continuous flow — System at
Salisbury, England — In Italy — In Belgium — Mountain
meadows 359-365
Irrigation of Cranberries. — Laying out the marshes — Rapid
flooding and draining — Irrigation of small fields by
pumping 365-368
Irrigation of Bice Fields. — South Carolina system — Trunks
— Germinating the rice — Dry hoeing — Irrigation after
dry growth stage — Prevention of red rice — Upland irri-
gation 368-373
Orchard Irrigation. — Furrow method best — Capillary
spreading of water — Distributing flumes — Foot ditch —
Watering by ring furrows 373-381
Cultivation after Irrigation. — The cardinal principle —
Forms of orchard cultivators — Importance of cultiva-
tion in humid climates 381-383
xviii Contents
PAGES
Small Fruit Irrigation. — Frequent irrigation needed for
strawberries — Watering alternate rows to facilitate
picking 383, 384
Garden Irrigation. — Bed irrigation — Bailing system — Ridge
and furrowmethod— Basin flooding— At Gennevilliers —
At San Bernai'dino 384-391
Irrigation of Lawns and Parks. —Inadequacy of spraying —
Rainfall of humid climates not usually sufficient 391-396
Sub-irrigation. — Not economical of water — Water not ap-
plied where most effective — Unequal wetting of the
soil — First cost heavy — May be applicable in certain
cases 396-402
CHAPTER XI
Sewage Irrigation (pages 403-414)
Objects Sought in Sewage Irrigation. — Destruction of or-
ganic products — Utilization of fertility carried 403
Climatic Conditions Favorable to Seicage Irrigation . — Warm
climates best suited — Cold soils chiefly filters — Large
area required for winter handling 404, 405
Process of Sewage Purification by Irrigation and Intermit-
tent Filtration. — Essential conditions — Effect of too
rapid application 405, 406
Soils Best Suited to Seicage Irrigation. — Lighter loams and
sandy soils— Any soil adapted if area is sufficient 406
Desirability of Wider Agricultural Use of Sewage in Irriga-
tion.— Exarmples of valuable results — Sections of country
specially adapted to it 406-409
Crops Suited to Sewage Irrigation. — Grass, most generally
— Soil for intertillage crops fertilized by winter irriga-
tion — Potatoes at Croyden — May injure grass if applied
in winter 409-413
Influence of Sewage Upon the Health. — At Gennevillitrs —
Purity of effluent compared with well water 413, 414
Contents xix
Part II
FARM DRAINAGE
CHAPTER XII
Pkinciples of Drainage (pages 415-466)
PAGES
TJie Necessity for Drainage. — Removal of injurious salts —
Better soil ventilation — Makes the soil more firm 416, 417
The Demands for Air in, the /So//. — Supply of free oxygen —
To lessen denitrifieatiou — Facilitates chemieal changes- . 418, 419
How Drainage Ventilates the Soil. — Permits roots and bur-
rowing animals to go deeper — Develops shrinkage
checks — Favors granulation of soil — Barometric and
temperature changes — Suctional effect of rains 419-421
Too Thorongh Aeration of the Soil. — Leads to destruction of
humus — Care of open soils 421,422
Drainage Increases the Supply of Available Moisture for
Crops. — Deeper root penetration — Stronger capillarity
— Stronger nitrification — Deeper ground water more
available 422, 423
Soil Made Warmer by Drainage. — By lessening surface
evaporation — By lowering specific heat — Observed
dift'erenees of temperature 423-425
Importance of Soil Warmth. — Relation to germination —
Hastens development of plant-food 425-428
Conditions under ivhich Land Drai)iage Becomes DesiraMe. —
Lands subject to frequent overflow— Lands with strong
underflow near surface — Tidal plains — Flat lands with
heavy subsoils 428
Origin of Ground Water and its Relation to the Surface.—
Vertical movement of rains — Surface of ground water
Lines of flow — Growth of rivers 429-435
XX Contents
PAGES
Rate at which Ground Water Surface Rises away from the
Drainage Outlet. — In tile-drained field — Where not
tile-drained 435, 436
Depth at which Drains should be Placed. — Kind of crop —
Seasonal changes of ground water — Character of soil —
Distance between drains 436, 437
Distance Between Drains. — Texture of subsoil — Depth of
drain — Interval of time between rains or irrigations —
Climatic conditions 437, 442
Kinds of Drains. — Closed — Open — Stone — Wood — Brick
—Peat— Tile— Cement 443-445
How Water Enters Drains. — Rate through the walls —
Through the joints — Care in making close joints — Use
of collars 445, 446
Fall or Gradient of Drains. — Highest practicable — Selecting
course for the main — Care in laying to grade — Change
of grade — Use of silt well 447-449
Size of Tile.— 'So specific statement possible except where
all details are known — Size increases with length —
Seldom smaller than three inches in diameter — Example
of sizes and lengths 449-452
Outlet of Drains. — Should have a clear fall — Precautions
against injury from frost — Connecting laterals with
mains 453, 454
Obstructions to Drains. — From roots— Kinds of trees most
troublesome 455, 456
Laying Out Systems of Tile 456-459
Litercepting the Underflow from Hillsides 459, 460
Draining Sinks and Ponds. — By intercepting surface drain-
age — By subdrainage 460-462
T}ie Use of Trees in Drainage 462, 463
Contents xxi
PAGES
Tlie Use of the Windmill in Drainage. — Arrangement for
winter pumping — Subirrigation as an adjunct 463, 464
Lands tchich must be Surface Drained. — Ancient lake bot-
toms underlaid with clay — Sections where there are no
natural surface outlets 464-466
CHAPTER XIII
Practical Details op Underdraining (pages 467-492)
Methods of Determining Levels. — Kinds of levels 469-471
Leveling a Field. — Making contour map — Using the level. • 471-473
Location of Mains and Laterals. — Securing the greatest
fall 474-476
Staking Out Drains. — Grade pegs 476, 477
Determining the Grade and Depth of Ditches. — Method of
marking stakes for use of ditchers 477-481
Mwe than One Grade on the Same Drain 481
Digging the Ditch. — Tools used — Method of procedure —
Methods of filling 481-488
Cost of Underdraining. — For mains — For laterals 489-491
Feat Marshes 491, 492
IRRIGATION AND DRAINAGE
INTRODUCTION
GENERAL BEMABES ON THE IMPOBTANCE OF WATER
The watering of laud, which is irrigatiou, and the
withdrawal of such part of that water as does not
evaporate, which is land drainage, are two methods,
one the opposite of the other ; but, looked at in the
broadest sense, both are natural, and each is as old
as the time when the rains descended upon the first
lands which rose above the ocean's level. The periodic
watering and draining of the earliest rock fragments
which covered the earliest lands, and which came to
be the earliest soils, constituted at once the most
primitive, the most profound, and the most persis-
tent environment to which all forms of land -life
have been forced to adapt themselves.
Since the very earliest forms of life probably came
into being in the water, and were composed in large
measure of it, it is not strange that we yet know of
no forms which can live without water, and to which,
indeed, water is not the most fundamentally important
substance and food. It is so, not more because it
makes up so large a part by weight of all living and
A (1)
fMKffTT jjntunr
2 Irrigation and Drainage
growing parts of plant life, than because it is the
medium in which the transformation of the crude
materials into assimilable food -products takes place,
and through and by means of which these products
are transported to their destinations at the various
points of growth. It is only when we fully appreciate
the important role played by water in crop production,
that we are in position to see how necessary to large
yields is the right amount of water at the right time,
and thus be led to insure to our crops a sufficient
irrigation and an adequate drainage.
Since the falling of rain upon soils has alwaj's
been intermittent in its character, and during the in-
tervals of fair weather a part of the water so given
to the soil has been lost by drainage, land vegetation,
during its evolutionary stages, has become fitted to do
its best work when the soil is watered once in about
so often, and when that soil retains a certain amount
of the rain which falls. But the intervals between
rains in almost all countries are irregular in length,
and the ainount of rain which falls at one time also
varies between very wide limits, so that in many if
not in the majority of climates, those seasons are rare
indeed when a crop can be carried to maturity with
the soil containing at all times the best amount of
moisture. This being true, there will occur times with
almost all soils when they would give larger yields if
they could be artificially irrigated or artificially drained,
according as the period is one of deficient or of exces-
sive rain.
But not all soils are alike in their capacity for re-
Soil Texture in Eelation to Rainfall 3
taining' moisture and of permitting it to drain away,
and this being true, under one and the same conditions
of rainfall one field might be benefited by irrigation
while another one would profit by better drainage.
It is this fact of varying capacity of soils to store
water for given periods of time that, in the long strug-
gle for existence and of fitting and refitting among
plants, has led to the evolution of certain species
which can thrive best in a soil of coarse texture, re-
taining but small amounts of water for any length of
time, while other species have become adapted to the
soils of finer texture and higher water capacity. This
is a fact of fundamental importance, not only in decid-
ing what crops may be grown in a given soil, but
whether or not it will be desirable to irrigate such
lands beyond the natural rainfall.
A soil of fine texture is spoken of as the best grass
laud, for example ; but this has reference, in a very
large degree, to a certain amount and frequency of
rainfall, which chances to be such as to maintain for
the grasses the amount of water in the soil under
which they have become accustomed to grow best. If
there were another soil in the same locality, of similar
composition but of coarser texture, and so of smaller
water capacity, it is most probable that this soil would
be converted into equally good grass land, giving just
as large or even larger yields per acre, if only the
natural rainfall were supplemented by artificial irri-
gation, so as to hold the water of the soil up to that
quantity which the grass has become accustomed, by
long breeding, to use.
4 Irrigation and Drainage
Then, again, on the other hand, the soil which for
a given climate is so close-grained that it does not
drain sufficiently between rains to leave it dry enough
for those crops which have become accustomed to the
smaller water capacity of the coarser soils, may be all
right for the dry- soil crop, provided it occurs in a
locality of smaller or less frequent rainfall. Or, again,
in the region of heavier rainfall, this soil may be fitted
for the dry-soil crop by thorough under-draining, when
the lines of tile are placed close enough to draw down
the water to a sufficiently low point to leave the soil
with the amount of moisture which is suited to the
crop in question.
Another soil may be very deep and exceptionally
well aerated, on account of its peculiar texture, ■ so
that the roots of cultivated crops easily penetrate it to
much greater depths than is possible in the closer,
more compact, non-aerated subsoils of other localities.
When this is the case, as appears often to be true
in arid and semi -arid climates, notably in parts of
the San Joaquin Valley, in California, the smaller rain-
fall of the winter season penetrates the soil so deeply,
and returns to the surface by capillarity so slowly, that
fair and even large crops are often raised on these
soils without artificial irrigation, yet not a drop of
rain may fall upon the land from May first to Septem-
ber. So different are the conditions in humid soils, like
those of the eastern United States, that even a period
of ten days without rain, especially if it occurs in the
height of the growing season, is sure to bring marked
distress even to field crops like maize.
Apparently Sigh Service of Water 5
One of the most striking features of the arid sec-
tions of the United States, which attracted the writer's
attention during his travels tlirough the West, was this
apparently greater service of water in crop production
than is realized in the more humid climate of the east-
ern section of this conntr3^ Reasoning from general
principles, one is naturally led to anticipate that in an
exceptionally dry atmosphere and under a clear sky,
such as we have in the western United States, the rate
of evaporation, both from soil and vegetation, w'ould
be exceptionally rapid, and hence that enormous quan-
tities of water would be required in crop production,
when compared with the demands of crops under more
humid conditions.
Such, however, does not appear to be the case, and
it is this fortunate relation which makes it possible
for larger areas to be placed under irrigation with the
limited amounts of water than would be possible were
the conditions of the soil more like those of humid
climates.
It is not easy to assign a thoroughly satisfactory
set of reasons for this marked difference without a
more detailed study of the field conditions than hag
yet been made. It seems quite probable, however, that
prominent among the reasons to be assigned for these
differences is the one to which reference has already
been made : namely, the texture of the soil, which
allows the water to distribute itself evenly and rela-
tively deep in the soil, and it does not return
readily and rapidly by capillarity to the surface to be
lost.
6 Irrigation and Drainage
In passing south from San Francisco, through Lath-
rop, Merced and Fresno, to Bakersfield, in California,
we pass across a long stretch of country where there
is at present relatively very little irrigation, and yet
through all of the country north of Merced wheat has
been extensively grown, and during the early years,
when the soil was new, large yields per acre have been
realized without irrigation, the crop depending upon
the rain which falls during the rainy season of winter
and sinks into the soil, to be later used by the deeper
feeding roots. lu discussing the matter with Professor
Hilgard, he informed me that the roots of crops
penetrate these soils much more deeply than is normal
to them under other conditions, and that some plants,
when brought here, really change their habits of root
growth through a dying off of the normal surface
feeders on account of an insufficiency of moisture in
the upper layers.
Professor Hilgard further informed me that over
much of the state of California the rains only wet
down a relatively short distance, and that beneath this
zone of moistened soil the balance is often almost
air -dry, extending, in certain eases which have come
under his observation, to depths as great as forty feet.
Where such conditions as these exist there is, of
course, no possibilitj^ of crops deriving a supply of
moisture through natural sub -irrigation from waters
from the foothills or higher mountain masses which
rise above the plains.
My own observations on the soils of humid cli-
mates convince me that the zone of dry soil, to which
Apparently High Service of Water 7
reference lias been made must act as a powerful ad-
junct in the retardation of both capillary and gravi-
tational movements of water below the reach of deep
root feeding ; and if this is true, practically all loss of
water by downward percolation is prevented, and the
whole rainfall not lost by surface evaporation becomes
available for crop production.
There is another condition, brought about by the
presence of the" layer of air - dry soil beneath the
moisture -bearing zone, which in humid regions only
exists in exceptional localities, and which may have an
important influence in making a larger part of each
year's rainfall available for crop production. I refer
to the possibility of the large amount of air stored in
the air -dry soil beneath the moist layer contributing
to deep soil breathing. By slow diffusion upward, and
by movements induced by changes in atmospheric pres-
sure, the roots may be supplied with oxygen from be-
low as well as from above, and thus have their feed-
ing depth lowered on this account beyond what is
usual in humid soils. So, too, it appears to be quite
possible that nitrification and other biologic processes
may be permitted to go forward under these condi-
tions, when in humid soils they are largely prohibited
for lack of sufficient aeration.
These suggestions, however, do not appear to offer
an adequate explanation of the ability of crops to
reach maturity in the arid soils of the West without
irrigation, when there is no rain for such long inter-
vals ; for, as we approached Merced from the north, a
very sandy belt of land was passed which was white
8 Irrigation and Drainage
and glistening in the sun, and which drifted as badly
as much of apparently similar land in Wisconsin, and
yet on these coarse sands wheat was being harvested
which would give larger yields than would be expected
on such lands in Wisconsin with a summer rainfall
of not less than ten inches. But here the crop had
stood and matured from early May until the end of
July without irrigation and without rain. One is led
to question whether it may not be • true that, under
the stress of such arid conditions of both atmosphere
and soil, plants of some kinds may develop a texture
of a closer nature, with fewer and smaller breathing
pores, and thus reduce the loss of moisture through
their surfaces much below what is normal to the same
species under more humid conditions of soil and atmos-
phere. Such a question could, of coiirse, readily be
settled by a proper comparative study of tissues de-
veloped under the two conditions ; but, so far as we
know, it has not yet been done. It should be said,
however, in this connection, that the seemingly greater
service of water to which reference is here made may
be more apparent than real. The climate of the region
being warm, and wheat being sown from the begin-
ning of the rainy season in November until the end
of Januarj^ there is much time for the crop to germi-
nate, and to get its root system thoroughlj- established
in the ground, and to have made a very considerable
growth, before the close of the rainj- season early in
May. There are left, then, only the months of May
and June during which the crop must complete its
growth without rain. It is true that this is a long
Advantages of Abundant Moisture 9
period, and in humid climates, where the growth of
vegetation can only begin in March or April, even
though the rainfall were the same as in the San Joaquin
Valley, crops like wheat could not be matured ; and it
is quite possible that this would also be true of the
countr}' in question did it have an ice-bound winter.
In the vicinity of Fresno, California, where a large
acreage of raisin grapes are grown on a sandj'' loam,
generally without irrigation, it is the belief of many
of the growers that their vinej^ards derive not a little
moisture through a seepage from the canals and ditches
of the district, whose waters are more generally used
in the irrigation of alfalfa ; but, as many of these
vineyards are considerable distances from both canals
and ditches, it is, perhaps, more probable that the
grapes survive through extremely deep and wide root-
feeding and, perhaps, small foliage evaporation. It is
the naturally small water capacity of the Fresno soils,
and those referred to near Merced, which makes it so
difficult to understand how, even with very wide and
deep root-feeding, moisture enough could be gathered
to maintain growth and carry a crop to maturity
without rain during the summer season, and without
ii'rigation.
ADVANTAGES OF AN ABUNDANT SUPPLY OF
SOIL MOISTURE
While there are such cases as those cited above,
in which plants appear to thrive and to produce fair
yields with relatively small amounts of water, yet it
10 Irrigation and Drainage
is a matter of universal experience in humid climates
that on clayey soils heavy protracted spring rains con-
tribute more to the production of large crops of grass
than all the manure which farmers can put upon their
lands, and that with dry springs fertilizers, of what-
ever sort and however applied, are of but little avail.
So, too, four weeks of copious, timely, warm rains fall-
ing upon fields of potatoes after the tubers begin to
set, and of corn after the tassels and silk begin to
form, are certain to be followed bj' enormous yields,
even when the soil is not rich, unless frost or disease
intervenes. On the other hand, let the tuber and grain-
forming period of these crops be one of drought, and
it is only those soils which are most retentive of mois-
ture, and which have been most skillfully handled, that
are able to mature even moderate yields, though the
land be very rich.
What, then, do warm spring and summer rains and
warm, sweet irrigation waters do in the soil which con-
tributes so much to plant growth ? In the first place,
it is only through the soil, where very extensive absorb-
ing surfaces of root hairs are developed, that plants
are able to obtain the very large amounts of water
they need for food and for the maintenance and carry-
ing forward of the physiological processes which are
associated with plant growth.
But it is not alone for the crop which is being grown
upon the ground that water is needed in the soil ; for
it must never be forgotten that there are living within
the dark recesses of the soil organisms of various kinds
upon whose normal and vigorous activity depends, in
Advantages of Abundant Moisture 11
a high degree, the magnitude of the specific crop which
is to be harvested. The germs which react upon the
dead organic matter in the soil, converting it into
ammonia, the germs which change the ammonia into
nitrous acid, and the germs which transform the nitrous
acid into nitric acid, — which is the real nitrogen supply
of most of the higher plants, — each and all are depend-
ent for their proper activity upon the right amount of
moisture in the soil. Then, there are those symbiotic
forms of lowlj^ organisms whose great mission it is
to take the free nitrogen from the air and compound
it into such forms as shall leave it available for the
higher plants, and which, like all other forms of life,
must have water and to spare if they are to perform
their work. Let the water content of any soil be
reduced below a certaiu amount, and all of these vital
processes are inevitably slowed down ; let it be reduced
to a still lower degree, and the whole line is at a com-
plete standstill.
Now, in humid regions, where the subsoils are much
of the time water -logged, and where, as a consequence
of this, there is but little soil ventilation, the plant-
food builders to which reference has just been made
are all of them forced into a thin zone close to the
surface of the ground, where their work must all be
done ; but if this surface zone is allowed to become
dry, then the nitrogen -supplying processes must come
to a standstill, and the crop which is growing above
the ground must have its growth checked, even though
it has put its roots down into the subsoil where mois-
ture for its own purposes may be had. Indeed, we may
12 Irrigation and Drainage
well believe that one of the chief causes which has led
the higher plants to send their roots foraging so deeply
into the ground is this great need of water in the sur-
face layer, where the nitrogen suppliers dwell, and for
the express purpose of not drawing upon this supply
too extensively, and thus leaving the surface soil to
become too dry. It is true that when heavy rains
come, or when irrigation waters are applied which lead
to the percolation of water downward, the nitrates
which have been formed at and near the surface are
dissolved and more or less completely washed more
deeply into the ground, where the deep -running roots
are in position to take advantage of them and prevent
their being lost ; and thus a double gain is secured.
Let us call attention to another important principle.
In the soils which have been highly manured, or which
are naturally well supplied with organic matter ready
for decay, large amounts of nitrates are rapidly formed.
Under such conditions the moisture which invests the
soil gi-ains rapidly approaches saturation, and finally
reaches a point when it is carrying so many salts in
solution that the water is no longer suitable for the
use of the germs which have given rise to the salts,
and their activities are on this account brought to a
standstill. But let a rain come which produces perco-
lation, or let the field be irrigated sufficiently to pro-
duce the same effect, and at once the salts which have
been inhibiting the nitrate -forming process are washed
out and a fresh sifpply of water is left, which at once
becomes a stimulus for increased activity, while the
ready -formed salts containing nitric acid are carried
Fertility Influenced by Drainage 13
to a lower level, where they may be taken up by the
deeper -feeding roots. Here, then, we are led to see
one of the ways in which water, applied at the sur-
face at opportune times, acts as a wonderful stimulus
to plant growth.
If, now, we turn from the irrigation to the drain-
age side of the same problem, we shall see in another
way how fundamentally important this principle is.
Let a soil be inadequately drained, and the roots of
the plants will be forced to occupy the surface soil,
for they cannot abide in the water -logged region.
Then, if heavy rains come and percolation results, all
of the unused nitrates which maj^ have been in the
soil at the time are at once washed below the roots,
and perhaps entirely lost to the crop. But, on the
other hand, if the soil had been properly drained, so
that the roots of the crop could have been two, three
or four feet below the surface, then, as has been pointed
out, the nitrates would have been washed to the roots,
where they would have become at once available.
Then, too, when a dry period comes, with all the life
processes going on in the soil confined close to the
surface, the great demand for water from the roots
forces them at once to so completely dry out the sec-
tion they occupy that a violent check is at once put
both upon the plant itself and upon all the food-form-
ing processes in the soil ; for, under these conditions,
it is usually impossible for capillarity to keep pace
with the loss of water from above, and the soil quickly
becomes too dry.
So far we have been speaking of the importance of
14 Irrifjdtion and Drainage
water in the soil to the direct vital processes which
are going on there whenever steady growth is taking
place. But there are other processes which are purely
physical, to which attention needs to be called before
we have brought into view the full line of operations
to which this great agent, water, leads.
Other plant-foods, — those which contain the phos-
phoric acid, potash, lime, magnesia, iron and sulfur, —
must be taken from the inert solid form in the soil
into solution in water before they can be of any service
in plant growth, and this is another of the important
roles which water has to play in the life processes of
the soil. Then, too, all water used in irrigation, and
even rain water, contains^ larger or smaller quantities
of plant -food, either directly in solution or borne in
suspension, which adds so much to the fertility of the
soil itself.
So, too, all waters which have been exposed to the
atmosphere have become charged with oxygen, carbonic
acid and nitrogen, which they carry with them into
the soil, and these always aid, in one way or another,
both the physical and the life processes which make
for fertility of the land. And, again, when a large
volume of warm water falls upon or is applied to the
soil, and it sinks deeply into it, it carries with it not
only its own warmth, but also the heat which it may
have absorbed from the surface of the ground ; and
this warmth, carried deeply into the ground, makes
the root action stronger and at the same time increases
the rate of solution of plant -food from the soil grains.
When we have made this brief survey of what warm
Water only One of the Necessary Plant -foods 15
rains and sweet irrigation waters do in the soil, we
may not be surprised to see the large jdelds of grass
or of potatoes or corn it is capable of helping the
soil and the sunshine to bring forth as the product
of a summer's work.
WATER ONLY ONE OP THE NECESSARY PLANT -FOODS
In view of the facts which have just been pre-
sented, it is not at all strange that the ancient Egyp-
tian and Grecian philosophers, with their lack of exact
knowledge and under their arid climatic conditions,
should have come to believe that water is the sole
food of plants ; nor that this opinion should have
been held until nearly the beginning of the eighteenth
centur}'. As a matter of fact, water does contribute
more than half of the materials which make up the
dry matter of plants, and, as water, it constitutes from
three -fourths to more than nine -tenths of their green
weight.
But while these are the facts, and while it is true
that abundant and timely rains do make compara-
tively poor soils produce large yields, it must not be
inferred that, with ample and timely supplies of water
applied to the soil, all else may be neglected and the
hope entertained that any agricultural soil will thus
be held up to a high state of productiveness for an
indefinite term of years.
It is a matter of universal experience that sewage
waters, not contaminated with poisonous compounds
and not too highly concentrated, cause lands to give
16 Irrigation and Drainage
much larger returns in grass than do river, lake or
well waters. The writer learned, while visiting the
celebrated Craigentinnj' meadows near Edinburgh, that
the purchasers of the grass from those lands are very
particular to specify, as a condition of their purchase,
that their grass shall be watered with the day sewage,
which contains a higher per cent of soluble and sus-
pended organic matter than that of the night ; and
they are also particular to stipulate that they shall
have the first rather than the second or third use of
the water, knowing that water which has passed over
a cultivated field or meadow has lost something of its
fertilizing value.
It is asserted, also, by the owners and renters of
water meadows in the south of England, where the
irrigation is directly from the streams, that that land
which receives the water first is most benefited by it.
It is true that there are those who contend that on their
lands the second and third waters are as good as the
first, but this is quite likely to be due to the presence
in those particular soils of an abundance of the sub-
stances carried by the waters.
It is, however, impossible to overestimate the im-
portance of water as a plant-food. It is indispensable
and is used more than any other substance. It must
be borne in mind, however, that irrigation waters are
seldom, if ever, a complete plant-food.
THE AMOUNT OF WATER USED BY PLANTS
The amount of water which is required to mature crops of
various kinds uuder field conditions varies between wide limits ;
Amount of Water Used bij Plants 17
but just what are the precise factors, and what their quantitative
relations, is not yet so definitely known as it needs to be. The
problem is manifestly a complex one, and many of the factors
are obscure, and will only be made known in their quantitative
relations after much patient critical work has been done having
for its prime object the solution of this problem.
It has already been pointed out that there appears to be
relatively less water consumed in the production of a pound of
dry matter under some of the conditions which exist in arid
America than is required in the more humid sections of this
country, and that it appears probable that a part of this differ-
ence is to be sought, possibly, in adaptive functions in the plant
itself and a part in the differences of soil conditions.
Under the natural conditions of the field, it would be expected
that very much will depend upon the character of the season ;
that is, whether the season is humid or dry, whether the tempera-
tures are high or low, whether the wind velocities are strong or
light, and whether the amount of sunshine is more or less. Very
much, too, will depend upon the soil and the character of the
rainfall, whether the soil is open and the rains are frequent and
heavy, so that considerable amounts of water are lost to the crop
by percolation and under-drainage, or whether the soil has a
retentive texture, and the rainfall is so proportioned that rela-
tively small amounts are lost, nearly all being used in the pro-
duction of the crop. Then, too, the manner in which the crop is
disposed on the field, whether it covers the surface closely, as do
the grasses and small grains, or whether considerable areas of
the field are exposed to the direct action of wind and sun, as in
many of the hoed crops and in orchards, must have a marked
influence in determining the actual amount of water which will
disappear or will need to be applied during a season, in order
to maintain the best moisture conditions for the particular
crop.
Then, again, the treatment of the soil itself will have much
to do with the quantity of water which disappears at once from
the surface without in any way benefiting the crop, and also the
quantity which drops at once entirely through the root zone, con-
B
18 Irrigation and Drainage
tributing nothing to the physiological processes which are involved
in tiie production of the harvest sought.
Irrigation and land drainage are, each of them, methods of
treatment of field conditions which aim to modify and control the
quantitative relations of the water which the soil shall contain,
and hence it becomes a matter of importance to know how much
water is necessarily involved in the production of a given amount
of a given crop. Much work has been done by various investi-
gators bearing upon this problem, but in all of those cases the
work has been by methods and appliances which have placed the
plants experimented with under such conditions that the roots
were forced to develop in a volume of soil which was much smaller
than field conditions usually afford. In the writer's work, how-
ever, he has aimed to give the i^lants more nearly the normal
amount of root room ; and in one series has aimed, also, to so
place the experiment that the plants should be growing as
nearly as possibly under the meteorological conditions of the field
crop.
The apparatus used for this work is illustrated in Fig. 1,
where, for the first trials, 50-gallon vinegar casks were used for
pots in which to place the soil. But after the first year's work
these were abandoned, and there were substituted for them, for
the field work, galvanized iron cylinders 18 inches in diameter and
42 inches deep. These were placed in pits in the ground in the
field, as illustrated in Fig. 1, so that the tops of the cylinders
were at the level of the top of the field soil, and so that the cylin-
ders in which the expei-imental plants were growing stood in the
field surrounded by the crop of the same kind growing under field
conditions. The object of placing the experiment in this manner
was to secure for the plants, as nearly as possible, the meteorologi-
cal conditions of the field, and these conditions were quite closely
realized in all particulars except the one of soil temperature. In
this particular the cylinders, being necessarily isolated from the
body of the field soil in order that they might be weighed at any
time, allowed the soil to take more nearly the temperature of the
atmosphere than was true of the deeper layers of soil in the field,
and also to be subject to wider diurnal changes in the lower por-
Water Required for a Pound of Dry Matter 19
Fig. 1. Method used to measure the amount of water required to produce
a pound of dry matter.
tions of the cylinders than could have occurred in the correspond-
ing depths in the field soil. Just how these differences of tem-
perature conditions have modified the results we are not yet in a
position to say, but it is not likely that they have caused very
20 Irrigation and Drainage
wide departures from what would have been observed had it been
possible to have measured as accurately the water consumed by
the surroundino^ plants of the same kind which were growing at
the same time in the field under every way normal field condi-
tions.
In all of these pot experiments, the efifort has been to hold
the amount of moisture in the soil at a constant quantity equal
to that which was possessed by the field soil in the spring of
the year, when it was in good working condition ; and this
was done by weighing the cylinders periodically, usually as
often as once a week, and then adding water in sufficient quan-
tity to bring the weight of the cylinder back to the original
amount. The cylinders were, of course, water-tight, so that the
only loss was through evaporation from the surface of the soil in
the cylinders and from the plants themselves. No effort has been
made in these experiments to distinguish between the amount of
water which actually passed through tlie plant and was evaporated
from its surface, and that which escaped from the surface of the
soil in which the plants were growing, as to do this would
necessitate the covering of the soil in which the plants were grow-
ing so as to prevent evaporation from it. To do this effectively
would interfere with the normal aeration of the soil, and thus viti-
ate the results by producing abnormal conditions. During the
work of the first year, when the wooden casks were used, there
was probably some loss of water through the walls of the casks,
due to capillarity in the wood and evaporation from it ; but
the amount was probably small, because they were all well
painted.
The first year's trials were with oats, barley and corn. With
the oats and barley the surface of the soil was not disturbed after
seeding, but in the case of the corn the ground was stirred after
each watering, so as to develop a soil mulch after the manner
of field culture. In each case the work was done in dupli-
cate. In the table which follows are given the results of these
trials :
Water Used by Plants 21
'Table showing the amount of water evaporated from plant and soil in producing
a pound of dry matter in Wisconsin in 1891
Dry matter Water per lb. of Water as inches
Water used produced dry matter of raiu
LBS. LBS. LBS. INCHES
Barley 1 158.3 .3966 399 14',
9 14 1
t.33/
Barley 2 141.03 .3488 404
Oats 1 224.25 .4405 509.311
Oats 2 220.7 .4471 493 63 J
Corn 1 300.45 1.0152 295.95
Corn 2 298.65 .9727 307.03
I 26.39
It will be seea from an inspection of the table that the sev-
eral experiments agree among themselves as closely as could be
expected, and that the barley used 13.19 inches of water in
coming to maturity, the oats 19.6 inches, and the corn 26.39
inches.
During the same season an effort was made to measure the
water required for a crop of corn under perfectly normal field
conditions. To do this two plots of ground, each 48 feet long
and 42 feet wide, were planted to a local form of Pride of the
North dent corn, in rows 3.5 feet apart and in hills 16 inches
apart in the rows, the corn being thinned to two stalks in a hill
after it had come up and was well established. At the time of
planting, samples of soil were taken in 1-foot sections to a depth
of 4 feet from six different places on each plot, and the water
in the soil determined. This was also done when the corn was
cut, in order to get a measure of the change in the water con-
tent of the soil, which it was proposed to add to the measured
rainfall of the growing season, to give the amount of water
used.
At the time of maturity, the whole of the corn of each plot
was cut and dried in a large dry-house, in order to get an exact
measure of the amount of dry matter produced. There is given
below the water content of the soil in the two plots at the time
of planting and at the time of harvest :
♦Eighth Annual Report Wisconsin Experiment Station, p. 126.
22
Irrigation mid Drainage
*Table showing the changes in the water content of the soil upon which corn had
been grown in 1S90 under field conditions
Dry weigh
cubic fo
t of soil per
ot
First foot
77.25 lbs.
PER CT. LBS.
Second foot
79.79 lbs.
PERCT. LBS.
Third foot
94.13 lbs.
PERCT. LBS.
Fourth foot
98.07 lbs.
PER CT. LBS.
..22.66 17.5
19.77 15.77
11.8 9.42
18.16 17.09
9.91 9.33
19.16 18.79
PLOT I
Sept. 16....
..15.75 12.17
10.77 10.56
Loss
... 6.91 5.33
7.97 6.35
8.25 7.76
8.39 8.23
...24.93 19.26
24.32 19.4
15.03 11.99
20.08 18.9
12.62 11.88
19.37 19
PLOT II
Sept. 16....
..18.43 14.24
9.8 9.61
Loss
.. 65 5.02
9.29 7.41
7.46 7.02
9.57 9.39
From this table it appears that each volume of soil four feet
long and one square foot in section lost the amounts of water
which follow:
Plot I Plot II
LBS. LBS.
Jjoss of water in soil 27.67 28.84
Rainfall from June 7 to Sept. 16 64.72 64.72
Total loss 92.39 93.56
17.76 inches 17.99 inches
The amount of dry matter produced in these cases was, for
Plot I, 450.18 pounds; Plot II, 455.36 pounds, making a yield per
acre of 9,727 pounds and 9,840 pounds for the two plots respectively.
Were it admissible to assume that the percolation of rain-
water below the zone of root action had been exactly equaled by
the rise of water into it by capillarity from the subsoil below, it
would follow, from the observed losses of water and yields of dry
matter, that the amount of water used for a pound of dry matter
under these field conditions was 413.7 pounds for Plot I, and 414.2
pounds for Plot II.
The results of a trial similar to the one just described, and with
the same variety of corn, for the year 1891, gave 309 pounds of
water for one pound of dry matter, on ground which had been given
a dressing of farmyard manure, and 333 pounds of water for a
pound of dry matter on land which had not been manured. Here
we have two trials by pot culture, where everything was under
♦Eighth Annual Report Wisconsin Experiment Station, p. 123.
Watey Used by Plants 23
control, and there could be no percolation, which gave an aver-
age of 301.49 pounds of water for a pound of dry matter. We also
have four field trials, where there is the uncertainty of some loss
of water by percolation and of some gain by capillarity from
below, which gave a mean of 413.95 pounds for 1890, and in 1891
321 pounds of water for a pound of dry matter. The amount of
percolation during the season of 1890 was certainly greater than it
was during the season of 1891, and this may or may not be an
explanation of the difference in the amounts of water used per
pound of dry matter in the two seasons.
In the case of oats grown under field conditions and studied
in the same manner as that described for the corn, the results
showed 519 pounds of water for a pound of dry matter in the one
case, and 534 pounds in another case, while the average of the
two pot experiments was 501.47 pounds of water for one pound
of dry matter.
So, too, in the case of field studies with barley, we had an
observed loss of 537 pounds of water in one ease on ground which
had been fallow, but 719 pounds on ground which had not been
fallow, for each pound of dry matter produced ; while the pot
culture gave a mean loss of only 401.74 pounds of water for a
pound of dry matter.
If we count the rainfall during the growing season and the
difference between the amounts of water in the soil at the time
of planting and at harvest, in the several field cases, as the
amounts of water used by the crop, including surface evaporation,
and then compare these amounts per square foot with those added
to the several pots in the pot trials, we shall have results which
are given below:
Table shotving number of pounds of ivater consimied per square foot
■ Oats .
In pots In field Difference
Mean amount of water per sq. ft.— lbs 101.98 72.98 29
' Barley >
Mean amount of water per sq. ft.— lbs 79.11 58.65 20.46
. Corn .
Mean amount of water per sq. ft.— lbs 137.3 C3.8 73.5
24 Irrigation and Drainage
From these figures it appears that while more water was lost
in the field, for each pound of dry matter produced, than in the
pot experiments, the amount of water used per square foot in
the pots was in every case much greater than it was in the field.
So, too, were the yields of dry matter, when expressed in
units of equal areas, much greater in the pots than they were in
the field. These relations are very suggestive, though, of course,
not at all demonstrative, that the larger amount of water used
per unit area in the pot experiments is to be credited with the
larger amount of dry matter produced per unit area. The differ-
ences are certainly in the direction we should expect if water
plays the important part we have attributed to it, and if in the
field experiments the several crops did not have all of the water
they might have used to advantage.
In 1892 pot experiments similar to those described were con-
ducted with barley, oats, corn, clover, and field peas, using gal-
vanized iron cylinders 18 inches in diameter and 42 inches deep,
placed in the field, surrounded by the field crop, and each experi-
ment being in duplicate. The results of these trials are given in
the table below:
Table showing the amount of tvater used in producing a pound of dry matter
in Wisconsin in 1S92
Water used
Dry matter
produced
Water per lb. of
dry matter
Computed yield
per acre
Water
used
LBS.
LBS.
LBS.
LBS.
INCHES
Barley 1..
.... 216.12
.576
375.21
14,196
23.52
Barley 2..
.... 206.12
Oats 1..
.... 174.6
.3322
525.59
8.189
19
Oats 2..
.... 167.58
Corn 1 . .
. ... 235.96
.9905
238.22
19,184
25
Corn 2..
.... 225.24
.5657
398.15
Clover 1..
.... 337.36
.5977
564.43
12,486
29.73
Clover 2. . ,
.... 348 66
Peas 1..
.... 155.24
.3252
477.37
8,017
16.89
Peas 2..
.... 139.17
If, now, we express the relation between the amount of dry
matter produced and the number of inches of water used in these
trials and in those of 1891, it will be seen that the yields of dry
nOPEKTr UBKAKT
M. estate CoOcfe
8,189
19
4,157
11.27
7.441
13.19
14,196
23.52
8,190.5
12.26
19,845
26.39
7,045.3
11.34
19,184
25.09
12,496
29.73
8,017
16.89
Water Used by Plants 25
matter per acre are measurably proportional to the amount of
water used by the crop in producing it. These relations are
expressed in the following table:
. In tlie field •■ In cylinders >
Dry matter Water \ised Dry matter Water used
LBS. PEK ACRE INCHES LBS. PER ACRE INCHES
Oats in 1891 6,083 13.93 8,861 19.69
Oats in 1892
Barley in 1891
Barley in 1892
Corn in 1891
('orninl892
Clover in 1892
Peas in 1892
Now, here, in the ease of the oats, the average yield of di-y
matter per acre in the cylinders was 4.26 tons, while in the field
it was 3.04 tons. But the soil put into the cylinders in the spring
was the same as that in the field and contained the same per cent
of soil moisture, but there was given to the soil in the cylinders
1.39 times the amount of water which fell as rain upon the sur-
rounding fields, plus the amount of water by which the soil was
dryer at harvest than at seed-time ; and we had a yield 1.4 times
as large.
In the experiment with barley, we had an average yield of
5.41 tons of dry matter per acre in the cylinders, but only 2.08
tons in the field. There were added to the cylinders 1.63 times
the amount of water which fell upon the field, plus the amount
of water by which the soil was dryer at harvest than at seed-time,
and we realized a yield of dry matter 2.6 times as large. There
was in the field a yield of 40 bushels of grain per acre, but in
the cylinders 104 bushels, and yet so far as we can see, the only
advantage the barley in the cylinders had over that in the field
was the increased amount of water added to the soil.
In the ease of corn, the yield of dry matter per acre in the
cylinders was nearly 2.6 times as large as that in the field, and
there was added to the soil in which this corn grew a little less
26 Irrigation and Drainage
■«
than 2.2 times the amount of water which was available for the
field crop.
In 1893, oats used water at the rate of 595 pounds per pound of
dry matter on a sandy soil where the yield was 1.196 pounds on
7.069 sq. ft., making a yield of 7,370 pounds of dry matter per acre.
But in this case the pot was a galvanized iron cylinder 6 feet deep,
standing above the ground, so that the evaporation would neces-
sarily be large, as the figures show it was. Expressed in inches,
the water used was equal to 19.37 inches of rain.
Clover, too, was grown in the usual form of cylinder in the
ground in the field, and two crops cut from each of two cylinders,
producing the yield and using the amounts of water stated below :
Dry matter per acre
Water per pound of dry matter
' — First crop —
-—Second
crop— -
No. 1 No. 2
No. 1
No. 2
LBS. LBS.
LBS.
LBS.
7,000 9,353
5,734 ■;
r,886
423.14 370.92
983.7
730.9
It will be seen that in these cases the first crops, which were
cut July 1, were much more economical of water used than were
the second crops, when measured by the standard of the number
of pounds of water per pound of dry matter produced. Express-
ing the water used in inches over the surface covered by the
crop, the results stand :
' First crop -—Second crop-^
No. 1 No. 2 No. 1 No. 2
INCHES INCHES INCHES INCHFS
Inches of water used 13.06 15.28 24.89 25.44
It is thus seen that the two crops of clover, averaging for
the four eases a yield of 7.493 tons of dry matter per acre, and
equivalent to 8.815 tons of hay containing 15 per cent of water,
used for the season a mean of 39.33 inches of water, an amount
which considerably exceeds the total annual rainfall of the year
for this locality.
Side by side with the clover trials of 1893, four cylinders were
treated in the same manner for corn, all of them growing a flint
variety. In these cases, too, one cylinder of each pair had its
Water Used by Plants 27
soil enriched with farmyard manure, to determine if a rich soil
affected in any notable way the rate at which water was used in
crop production.
The results of these trials may be stated as given below:
Flint corn- — - — ■ Flint corn ^
Manured Not man'd Manured Not man'd
12 3 4
LBS. LBS. LBS. LBS.
Dry matter per acre 34,730 33,620 22,540 9,505
Water used per lb. of dry matter 223.3 232 257.4
Water expressed in inches 34.23 34.42 25.56
223
The difference in yield between cylinders 3 and 4 and 1 and 2
appears to have been due to the condition of the soil at the time
the cylinders were fitted, the soil being more moist in 3 and 4,
which stood upon ground lower and too wet for conditions of best
growth. The field yield of corn surrounding the ej'linders, and
with the same kind of soil, was 4.4 tons of dry matter, yielding
66.95 bushels of kiln-dried shelled corn per acre, which is large
for field conditions with the normal rainfall. But the mean yield
in cylinders 1 and 2 was 17.09 tons of dry matter per acre, or
almost four times as mu«h, while the average of the four cylinders
was 2.85 times as large, but using 2.2 times the amount of water
which fell upon the surrounding fields as rain during the growing
season for this corn.
It does not, of course, follow from these experiments that well
tilled field soil, if irrigated properly, will produce such yields as
these which have been recorded ; neither does it follow, neces-
sarily, that these large yields owe their excess over normal crops
only to the extra supply of water added at the proper times.
It does, however, follow from these experiments, we think, that
were our water supply under better control and larger at certain
times than it is in Wisconsin, our field yields would be much
increased, if not actually doubled. It does follow, also, from
these experiments, that well drained lands in Wisconsin and in
other countries having similar climatic conditions are not supplied
naturally with as much water during the growing season as most
28
Irrigation and Drainage
crops are capable of utilizing, and, hence, that all methods of till-
age which are wasteful of soil moisture detract bv so much from
the yields per acre. Indeed, what we call good average yields
per acre are determined, in a large measure, by the amount of
soil moisture which the land is capable of turning over to the
crops growing upon it.
In 1894, work similar to that described was done with pota-
toes, eight cylinders being used, two of which were placed in the
Fig
Potatoes grown in cylinders to determine the amount of water
used in producing a crop.
field, as already described, and six others were kept standing upon
the surface of the ground, shaded on the south side from the sun
in the manner represented in Fig. 2, which shows the potatoes as
they appeared when growing. In the same year, oats were again
grown in four other cylinders surrounded by field grain of the
same kind, and in pots with their tops flush with the top of the
ground. A statement of the results of these several trials is
here given.
We give, in the first place, in illustration of the rate at which
potato plants use water in the various stages of their growth, a
Wfder Used hij Plants
29
table showing the times of waterins: ami the amounts of watei*
given through the whole growing season for the crop :
Table showinri
the times of watering
potatoes
, and the amounts of
water given
r-In
field —
/I i.
ders above gr
,
t'ylm
)untl
No. 1
No. 2
No. 1
No. 2
No. 3
No. 4
No. 5
No. 6
LBS.
LBS.
LBS.
LBS.
LBS.
LBS.
LBS.
LBS.
Weights at start
. 50-1
50G.7
581
576.5
579.6
579.7
582
579.5
May 15, water added
19.8
18.4
18.2
17.8
17.9
18.3
June 4,
. 10
10
June 13, "
. 10
10
10
10
10
10
10
10
June 21, " "
. 13
13
10
10
10
10
10
10
June 25, "
. 10
10
June 30, "
. 10
10
July 2. "
. 10
10
10
10
10
10
10
10
July 5,
. 15
15
10
10
10
10
10
10
July 9,
. 20
20
10
10
10
10
10
10
July 12, "
. 20
20
12
12
12
12
12
12
July 16, "
. 15
15
10
10
10
10
10
10
July 20. ■'
. 15
15
15
15
15
15
15
15
July 24. "
. 10
10
8.9
7.1
5.2
10.6
12
6
July 28. "
. 15
15
15
15
15
15
15
15
Aug. 2, "
. 10
10
10
10
10
10
10
10
Aug. 10, "
. 15
20
9.8
22.7
18
18.3
15.1
21.7
Aug. 16, "
10
10
10
10
10
10
Aug. 25, *
8.1
21.4
20.9
16.9
10.3
22.1
Weights at close
. 481.7
492
554
527.8
531.6
528.8
545.5
521.4
Total water added..
. 198
203
168.6
191.6
184.3
185.6
177.9
190.1
Soil water used
. 22.3
14.7
27
48.7
48
50.9
36.5
58.1
Dry matter
.5
.5
.3
.5
.5
.5
.4
.5
Total water
. 220.8
218.2
195.9
240.8
232.8
237
214.8
248.7
Water used, iu inches
. 24.02
23.74
21.31
26.2
25.33
25.78
23.27
27.06
The potatoes in the two field cylinders matured first, and were
dug on Aug. 25, while the others stood until Sept. 21. It should
be stated in this connection that all of the potatoes, including
those in the field, were affected by the hot weather blight, so that
in no ease were the plants in full vigor and presenting the normal
amount of foliage to the atmosphere.
The yields of tubers in the several cases, and the computed
yields per acre, figured as proportional to the surface and vol-
30
Irrigation and Drainage
ume of soil in which the crop grew, are given in the table be-
low:
Cylinders in the Ground
' Weight of tubers •
. Yield
per acre-
Merchantable
tubers
Small
Total
Merchantable
tubers Sui lU
Total
LBS.
LB.S.
lbs.
BU.
BU.
an.
No.l
1.308
.386
1.694
537.3
158.5
695.8
No^2
817
.775
1.593
335.6
318.3
653.9
Cylinders above Ground
No.l
452
.539
.991
185.6
221.5
407.1
No. 2
379
.792
1.171
155.7
325.5
481.2
No. 3
322
.875
1.197
132.4
359.2
491.6
No. 4
1.024
.314
1.338
420.6
128.9
549.5
No. 5
709
.282
1.091
291.2
1.50.9
448.1
No.6
681
.435
1.116
279.9
178.8
458.7
It will be seen from the relation between the weights of small
and merchantable tubers that the blight referred to had exerted a
very appreciable influence on the crop in all of the cases, so that
the relations which exist between the water used and the dry
matter produced cannot be regarded as normal. These relations,
as they were found to stand, are given below:
Table showing the pounds of water used by potatoes in producing a pound
of dry matter in tuber and vine in Wisconsin during the season of 1894
Dry raatter
LBS.
No.l 513
No. 2 5258
No.l 3338
No. 2 5007
No. 3 4505
No. 4 5020
No. 5 3596
No.6 5425
Water per lb. of
dry matter
LBS.
430.4
415
586 9
480.9
516.8
472.1
497.3
458.4
Cominited yield of
dry matter per acre
LBS.
12,650
12,960
8,248
12,340
11,110
12,370
8,865
13,370
Water used
INCUE.S
24.02
23.74
21.31
26.2
25.33
25.78
23.37
27.06
It is evident from this table, whatever may be said in
regard to the yields, that the potatoes did use a very large amount
Water Used by Plants 31
of water, although it was unquestionably less than it would have
been had the plants not been affected by the blight. As it was,
the plants received an average of 24.6 inches, which is three times
the amount of rainfall during their season, of growth.
It should be said further, in regard to the amount of water
used this season, that the whole of the watering was from the
bottom, so that the surface of the ground was kept dry throughout
the time. In order to introduce the water at the bottom, a layer
of sand was first placed in each cylinder before the soil was filled
in, and then a column of 3 -inch drain tile was set up against one
side, reaching from the bottom to the top of the cylinders, and in
adding the water it was poured into these tiles.
In the ease of the cylinders of oats which were grown in 1894,
they were watered in the same manner, so that in these eases
nearly all of the water used did actually pass through the plants.
The results with the oats are given below:
No. 1 No. 2 No. 3 No. 4
LBS. LBS. LBS. LBS.
Amount of water used 282.8 280.2 283.3 285.6
" dry matter produced.. .5232 .516! .4198 .4663
water per lb. of dry
matter 540.6 542.7 674.9 614.7
'" " dry matter per acre... 12,900 12,730 10,350 11,500
IN. IN. IN. IN.
Total water used, in inches 30.77 30.48 30.82 31.18
If reference is made to the yields of 1891 and 1892, which have
been given on a preceding page, it will be seen that the yields for
1894 have been decidedly larger than they were in the former
cases, but so were the amounts of water used by the plants. The
mean of the three earlier trials gives a yield of 8,525 pounds of dry
matter per acre, using 19.345 inches of water to produce it; but
in these last cases the mean yield of dry matter was 11,870 pounds
per acre, and the water used to produce it was 31.08 inches. The
yields of 1894 average 1.39 times the earlier ones, and the amount
of water used in producing this greater yield was 1.06 times the
amount required for the smaller.
32 Irrigation and Drainage
In 1895, aud again in 1896, similar experiments were carried
on with potatoes, barley and clover, both upon very sandy soils
and upon good clay loam. The first experiments described were
with potatoes on very stiudy soil taken from the pine barrens in
Douglas county, Wis., and which was ouite coarse-grained and
deficient in organic matter.
On June 3, 1895, the three cylinders in the right of the pho-
tograph, Fig. 2, were filled with the soil in question. Some 2,000
pounds of this soil had been procured from the surface down to a
depth of three feet. The first, second and third feet of the soil
were placed in them in their natural order in the field, the third
foot being at the bottom and the surface foot at the top, so as
to reproduce the natural conditions as closely as possible.
In cylinder 1, on the right, the soil was left in its virgin con-
dition; to No. 2 there was applied two pounds of well-rotted
farmyard manure, and to No. 3 there were given four pounds.
The remaining three cylinders, 4, 5 and 6, were used as checks,
and were filled to within 5 inches of the top with good surface
soil of a light clay loam character. In order that the tubers of
the potatoes might develop under as closely similar conditions as
possible, and that the surface evaporation from the soil might not
be very different, there was placed upon the surface of cylinder
4 five inches of the surface soil from the pine barrens, on cylin-
der 5 five inches of the second foot, and upon 6 five inches of the
third foot.
In planting, one tuber of the Alexander Prolific potato was
cut in halves and the two pieces planted, so as to give two hills in
each cylinder. The cylinders were weighed and watered once
each week, water enough being given to maintain a constant
weight.
In 1896, the cylinders were again planted in the same manner
with Rural New-Yorker potatoes. No fertilizers were used, but the
plants were watered twice each week, 5 pounds of water being
given to each cylinder every Monday morning and enough more
on every Thursday, when the cylinders were weighed, to bring
them to a constant weight. This change was made because it
appeared possible that the texture of the soil was too coarse to
2
3
4
5
6
BU.
BU.
BU.
BU.
BU.
862.6
801
1,089
1,119
883.2
450
284
279
416
152
412.6
517
810
703
731.2
IN.
IN.
IN.
IN.
IN.
27.91
■ 29.07
34.08
32.63
27.51
20 02
17.65
16 27
20.65
12.96
7.89
11.42
17.81
11.98
14.55
Water Used by Plants 33
permit a single watering every seven days to meet the needs of
the plants.
The results of the two years are given in the following table :
1
BU.
Yield per acre, 1896 513.5
• " " " 1895 74
Difference 449.5
Inches of water used, 1896 . . 25.85
" 1895.. 10.76
Difference 15.09
It will be seen from this table that both the yield of potatoes
and the amount of water used are much larger in 1896 than they
are in 1895, the average yield in 1896 being 878.1 and in 1895
only 275.8 bushels, the former being 3.18 times the latter. The
average amount of water used was 29.51 inches in 1896, and 16.385
inches in 1895, the former being 1.8 times the latter.
As a further cheek upon these experiments, two cylinders 7
feet deep and 4.33 feet in diameter were filled with a local yellow
sand, and to one of the cylinders farmyard manure was applied
at the rate of 50 tons per acre, .and to the other at the rate of 25
Ions per acre. These were planted in 1895 with Alexander Pro-
lific potatoes, seven pieces in each cylinder. The watering in
1895 was once each week, and twice each week in 1896. In the
latter year no fertilizers of any kind were applied, and Rural
New-Yorker potatoes were planted instead of the Alexander Pro-
lific. In 1895, 20.05 inches of water gave a yield of 605.5 bushels
on the heavily manured cylinder and 563.5 bushels per acre on
the other. But in 1896, when the potatoes were watered twice
each week at the rate of 75 pounds for the lightly manured ease
and 50 pounds for the other, the yield per acre on the lightly
manured cylinder was only 312 bushels, and yet 40.61 inches of
water were used; while the other cylinder gave a yield of 344.5
bushels per acre and used 31.92 inches of water,
C
34
Irrigation and Drainage
In this case it will be seen that a decidedly smaller yield is
associated with a much larger amount of water applied at shorter
intervals, but why this should be does not appear, unless the
manure had become exhausted and the plants were not properly
fed. The vines in all cases were abnormally small, and looked
starved.
In the experiments with both barley and clover, the small
cylinders were used set into the ground in the field. Two cylin-
ders were used for the barley and four for the clover, one -half of
them filled with the yellowish sand refen-ed to, well manured,
and the other filled with good soil. All the cylinders were
weighed and watered once each week, holding them at a constant
weight, and the results are given in the table below:
Barley, 1895
Sand Soil
Yield of dry matter in tons per acre 5.02 6.32
Bushels of grain per acre 30.17 38.14
Inches of water 25.84 31.24
' Clover, 3895 ■
Both crops
Sand Soil
First crop .Second crop Water used
Sand Soil Sand Soil inches .
Tons dry matter per acre, Xo.l.. 2.88 3.48 2.36 3.28 29.36 38.18
No. 2.. 2.91 3.25 3.19 2.77 37.15 39.91
Clover. 1896 .
Tonsdry matter per acre, Ko. 1.. 1.86 2.45 4.32 3.63 22.09 19.78
No. 2.. 2.09 2.9 3.62 3.29 20.87 20 48
Mean for two years 2.435 3.02 3.372 3.242 27.37 29.59
The mean annual yield of clover on the sand for the two years
was 5.807 tons of dry matter per acre, using 27.37 inches of
water, and the mean product for both crops on the good soil for
the two yeai*s was 6.262 tons of dry matter per acre, using an
average of 29.59 inches of water to produce it.
In addition to the field results which have now been presented,
measuring the water used in the production of crops in Wisconsin,
we have obtained some results in essentially the same manner,
except that the cylinders were made deep enough to contain four
Water Used hy Plants
35
feet of soil, and all were placed in the plant-house, arranged in
the manner shown in Fig. 3.
In these trials, two sizes of cylinders have been used : one 18
inches in diameter and 51 inches deep, and the other 36 inches
Fig. 3.
Method of growing plants in plant-house to determine the
amount of water used.
in diameter and the same depth. The large cylinders this year
have been filled with a black marsh soil, and the small ones with
a virgin soil of medium clay loam variety, taken from a second-
growth black oak grove.
First, the results obtained from four of the large cylinders
sowed to oats Dee. 12, 1896, and harvested July 1, 1897, after a
period of 200 days. The oats were sown thick, and grew very
rank, lodging quite badly.
The total dry matter and the total water used by the crop
of the four cylinders was as given below:
36 Irrigation and Drainage
No. of cylinders 13 14 23 24
Dry matter produeed-lbs 4 3.16 4.93 4.32
Total water used— lbs 1,808 1,668 2,061.5 1,782.5
Dividing the amount of water used on the four cylinders by
the dry matter produced, we get, as the mean of the four trials,
under the conditions of the plant-house, 446.1 pounds of water for
a pound of dry matter, and a yield of dry matter per acre amount-
ing to 12.G45 tons, which is very large, indeed. The water used
by this crop expressed as rainfall was, as a mean of the four
trials, 49.76 inches. Here is a depth of water used from this soil
which is a little greater than the soil itself ; but the rate at which
the water was used, it will be observed, is less per pound of dry
matter produced than that for the out-of-door experiments.
In the case of the clover on these black marsh soils, there
were eight of the large cylinders used, in four of which medium
clover grew, and on the other four alsike clover. These were
sown without a nurse crop, and at the same time as the oats, but
were cut July 8, so that the period of growth was 207 days. The
results obtained here with medium clover were as stated below :
No. of cylinders 15
Dry matter produced— gms 507
Water used— lbs 673.5
Dividing the total amount of water used on the four cylinders
by the total dry matter produced, we get 582.9 pounds of water
as tlie amount used per pound of dry matter. In this case the
yield of dry matter per acre was 3.92 tons, equal to 4.61 tons
of hfiy containing 15 per cent of water. The amount of water
used, expressed in inches, was 20.16.
The alsike clover gave yields and results as follows :
No. of cylinders 17
Dry matter produced- gms 628
Water used— lbs 809
In this ease, the mean amount of water for a pound of dry
matter was 581.5 pounds, and the yield of dry matter per acre
16
21
22
608
620
573
795.5
819
678
18
19
20
616
576
634
758
774
804.5
72
73
74
75
76
77
315.5
252.4
230
212.5
244.5
222.5
350
206
297
292.5
318
295.5
79
80
81
82
83
84
223.5
284.5
292.0
284.2
277.5
266.5
300.5
311.5
290
326.5
336
347.5
Wafer Used hy Plants 37
was 4.168 tons, equal to 4.9 tons of hay containing 15 per cent
of water. The water used, expressed in inches, was 21.43.
In the trials of clover on the virgin soil in the plant-house,
14 cylinders of the smaller size were used, and these were seeded
Dee. 12, 1896, and cut July 8, 1897. The yield of dry matter in
these cases per unit area was much heavier than on the black
soil, the amounts standing as below:
No. of cylinders 71
Dry matter— gms 312.5
Water used— lbs 373.5
No. of cylinders 78
Dry matter— gms 303.5
Water used— lbs 351.5
The total amount of water-free dry matter jjroduced on all
the cylinders was 3,724.2 gms., or 8.215 pounds., using 4,496
pounds of water, or at the rate of 547.3 pounds for one pound
of dry matter. The average yield of water-free dry matter per
acre was 7.23 tons, equal to 8.51 tons of hay containing 15 per
cent of water. The water used during the 207 days from seed-
time to cutting of the first crop was 84.93 inches.
Side by side with the cases now cited, six other cylinders
were planted to Rural New-Yorker potatoes on the same date.
These were dug July 2, and the photo-engraving, Fig. 4, shows
the crop produced. Although the potatoes were planted Dec. 12,
they did not come up until into February, apparently for no other
reason than that the tubers needed a certain period in which to
develop the conditions for growth, which at the time of planting
they had not had. When the plants did come up they grew very
rapidly. Below are given the results of these trials:
No. of cylinders 65 66
Weight of tubers— gms 1,288.7 808 1
Bushels per acre 1,168 732
Total dry matter— gms 342.6 263.6
Water per lb. of dry matter 275.4 .347.6
Water used by crop— lbs 208 202
Inches of water 22.63 21.98
67
68
69
70
1,370
1,313.4
1,27.5.4
1,204.8
1,249
1,189
1,155
1,091.5
332.5
334
312.2
328.8
281.7
272.3
307.3
306.3
206.5
200.5
211.5
222
22.47
21.81
23.01
24.15
38
Irrigation and Drainage
Here, again, if we figure the yield of dry matter per acre on
the basis of the amount of ground occupied, we shall have the
large crop of 8.67 tons of dry matter per acre, using in its pro-
duction 22.67 inches of water.
In twenty other 18-ineh cylinders in the plant-house, a variety
of white dent corn was grown, four plants in a cylinder. These
Fig. 4. Crop of potatoes using from 272-347 pounds of water for 1
pound of dry matter.
were planted May 22 and harvested Aug. 23, and on the twenty
cylinders, aggregating 35.34 square feet of soil, 18.1 pounds of
dry matter were produced, which used 5,685 pounds of water in
coming to maturity, or at the rate of 314.1 pounds of water for
one pound of dry matter, and a depth of water, when expressed
as rainfall, of 30.93 inches, the yield per acre being 22,310 pounds
of water-free matter.
Amount of Water Used hy Plants 39
VARIATIONS IN THE AMOUNT OF WATER USED
BY PLANTS
It is a matter of vei-y fundamental importance to know what
factors or conditions may cause a variation in the amount of water
which is necessary to produce a ton of dry matter, because it is
only by knowing these that it will be possible to lay down any
general principles for determining the amount of water which
will be required to produce a given yield.
If we examine the data which have been presented, it will
be observed that not only is there a rather wide variation in the
amount of water used by different crops, but, also, that there is,
further, a wide difference recorded as occurring with the same
species or variety, sometimes with the same species in the same
year, and sometimes for different years, and it is important to
know to what these differences are due.
In the case of corn, for example, where we have grown it
under the cylinder conditions in the field, the following varia-
tions have been noted :
In 1891, Pride of the North dent corn used in one ease 295.95
pounds of water for a pound of dry matter, and in the other 307.03
pounds. But in the first ease more dry matter was produced by
the individual plants, the first producing 4.369 per cent more than
the other did, but in doing this only .602 per cent more water
was taken ; that is, the most vigorous plants have produced the
most dry matter when measured by the amount of water used.
Indeed, it may be laid down as a general rule, that the more
favorable all conditions are for plant growth, the more effective
will be the water supplied to the crop. Good management, there-
fore, will "look closely to all details, even to the minor ones,
for everything counts in plant feeding just as it does in animal
feeding.
Not all varieties of the same species of plant use water in
the production of dry matter with the same degree of effective-
ness. In our work with dent and flirt corn, for example, we have
found, as a mean of four trials, that Pride of the North dent
40 Irrigation and Drainage
corn used water at the rate of 309.84 pounds of water per pound of
dry matter produced, and 25.74 inches of water when measured
in depth on the area occupied. But four trials with a variety of
flint corn gave a mean of 233.9 pounds of water per pound of dry
matter, which is 75.94 pounds or 32.5 per cent less than in the case
of the dent variety. This is not because actually less water was
used per unit area, for the flint corn in these four trials did use
a mean of 26.82 inches against 25.74 for the dent corn.
It seems not improbable that this more economical use of
water by the flint corn may be in part due to its lower habit of
growth and the greater abundance of foliage closer to the ground,
for it may be expected that the lower position of the leaves, and
their crowding as well, would tend to lessen the amount of
evaporation in a given time. But to whatever the difference may
be due, it is plain that on light soils and wherever the water
supply is limited, larger returns may be secured by paying atten-
tion to the variety of plant grown.
The amount of water used by a particular crop might be
expected to vary with the humidity of the season and the amount
of wind movement during the period of growth of the crop ; but
the data obtained do not appear to show so marked a relation as
would seem should exist. The mean relative humidity of the air
at Madison at 2 P. M., in 1891, for June, July and August, was
63.66 per cent, while in 1892, for the same time of day and period,
the mean was 68 per cent ; and the total wind movement for
Madison, these years, for the three months, as given by the
records of the Washburn Observatory, was 20,712 miles in 1891
and 18,870 in 1892. But in 1891, 26.39 inches of water gave a
yield of dry matter per acre of 19,845 pounds, and in 1892, 25.09
inches gave a yield of 19,184 pounds of dry matter per acre of
corn in the plant cylinders in the field. The differences in the
amounts of water used during the two years, it will be seen, is
very small, especially when it is recognized that in 1892 the dry
matter produced, and presumably the evaporation surface also,
was less than in 1891.
So, too, in the case of oats for these two years, 19.60 inches
of water gave 8,861 pounds of dry matter per acre in 1891, and in
Amount of Water Used by Plants 41
1892, 19 inches gave 8,189 pounds, leaving the rate of evapo-
ration from the plant surface very nearly the same for the two
seasons, in spite of the differences of humidity and of wind
A'elocities.
In the case of barley for these two years, there was a wide
difference in the amount of water used per unit area, 13.19 inches
being used in 1891 and 23.52 inches in 1892. But the yields of dry
matter per unit area were also widely different, being 7,441 pounds
of dry matter per acre in 1891 and 14,196 pounds in 1892. The
barley in 1891 used 3.54 inches of water per ton of dry matter,
and in 1892, 3.31, or only .23 inches less, which is small.
Even when the conditions are as different as those in the
plant-house and the open field, the differences are not as marked
as we were led to expect, as the table which follows will show:
No.
of trials
Aere-inelies of water
per ton of dry matter
Maize
8
2.433
Oats
8
5.011
Clover. . .
24
5.345
Total
40
Mean 4.263 T
In plant-house .
Acre-inches of water
No. of trials per ton of dry matter
44 2.386
12 4.535
22 5.005
Total 78 Mean 3.975
If the results are expressed in pounds of water used per
pound of dry matter, then they stand as follows :
Pounds of water per Pounds of water per
No.
, of trials
pound of dry matter No. of trials pound of dr
Maize
8
275.6 44 270.3
Oats
8
567.8 12 490.6
Clover . . .
24
605.5 22 567.1
Total
40
Mean 483 Total 78 Mean 442.3
The tables show that in the case of these crops — maize, oats
and clover — they have used in the field .288 acre-inches of water
more per ton of dry matter produced than in the plant -house ; or,
when expressed in the other way, 40.7 pounds of water per pound
of dry matter more in the field cylinders than in the cylinders in
the plant-house. Expressed in percentages, the field conditions
demanded 9.2 per cent more water when the cylinders stood out-
42 Irrigation and Drainage
of-doors, with the plants surrounded by the field crop and under
the out-of-door meteorological conditions, than they did in the
house.
This difference, however, shows larger than it really is, for it
has been shown that the use of water is usually more economical
in those cases in which the yields are largest, and in these eases
there has been a larger yield of dry matter per unit area in the
plant-house cylinders than were secured from the cylinders in the
field. The total mean yield per acre for the oats, maize and
clover in the field cylinders was 6.312 tons and in the plant-house
7.397 tons of dry matter per acre, making the latter yields on the
average 17.19 per cent larger; and to this difference in yield must
certainly be ascribed a part of the difference in the amount of
water given off from the plants and from the soil during the
periods of growth. It is quite plain, for example, that the loss
of water from the soil surface would tend to be relatively larger,
and probably, also, absolutely larger from the cylinders bearing
the smallest crop of a given kind. The absolute loss would cer-
tainly be largest from the cylinders where the crop had the thin-
nest stand on the ground, and some of the cases of larger yield
per unit area in the plant-house are due to the fact that more
plants occupied the same area.
While, therefore, from the general principles governing the
rate of evaporation, we are led to expect that more moisture must
be lost from vegetation growing in a dry atmosphere than under
more humid conditions, we are not able to point to our data as
bearing out such a view in any emphatic manner. The rate of
air movement in the plant-house has certainly been less than it
was in the field, but the higher temperature in the plant-house
has probably left the air relatively dryer during both day and
night than in the field.
The conditions which did exist, both in the plant-house and
in a field of maize, were noted on July 27, 28 and 29. The rela-
tive humidity of the air was measured with a wet-and-dry bulb
thermometer, and the rate of evaporation was also measured under
the two conditions with a form of Piche evaporometer. Two of
these instruments were hung among the corn plants in the plant-
Amount of Wafer Used hy Plants 43
house and two others in the field, one pair on irrigated ground
and the other on ground not irrigated.
The table below shows the variations in the rate of evapora-
tion observed in the three localities :
Plant house
IiTigated field
Field not
irrigat
No. 1 No. 2
No. 1
No. 2
No. 1
No. 2
c. c. c. e.
c. c.
c. c.
c. c.
c. c.
July 27
7 5.8
6.3
4.03
6.86
4.2
July 28
5.75 4.35
2.95
5.96
4.98
3.13
5.7
4.287
4.87
6.1
5.94
3.06
July 29
5.46 5.6
5.76
Mean
6.035 5.25
4.34
These rates of evaporation took place upon a surface of 27
square inches of wet filter paper.
The relative humidity observations were as here given:
Plant-house Irrigated field Field not irrigated
PEB CENT PER CENT PEE CENT
July 27 38 45 51 49 55
July 28 39.5 54 55 57 62
July 29 41 49 52 48.5 49
Mean 39.5 49.3 52.7 51.5 55.3
So far as these figures may be relied upon, it would appear
that the rate of evaporation in the plant -house may even have
exceeded that in the field, and if this was true during the time the
dry matter of the plant-house experiments was being produced,
then the indications are still less marked pointing toward an
increase in the amount of water being required for a pound of
dry matter in a dry, rapidly changing atmosphere, than is
required under stiller and more humid conditions.
It may be true that in the dry air a more rapid loss of mois-
ture from the plant does take place, and that this loss stimulates
a proportional increase of dry matter. This is merely a suppo-
sition, however, wi-th no experimental evidence to bear it out,
but such a tendency would give relations approaching those
recorded above. So, too, if the rate of evaporation is automatic-
44 Irrigation and Drainage
ally controlled by changes in the transpiring surfaces of plants,
and if this control is sensitive, then there would also be a ten-
dency to cause the amount of water necessary to produce a pound
of dry matter in a given species of plant to remain nearly con-
stant under wide ranges of climatic conditions. That most land
plants are provided with organs which modify the rate of trans-
piration has been long established ; but how narrow the limits
of control are remains to be demonstrated. It is fundamentally
very important that such facts as these should be established, for
they are needed in order that we may know how much land under
a given crop a given quantity of water will irrigate.
We have, at this writing, just completed a set of observations
bearing upon this fundamental problem, and although they are
not sufficiently extended to be demonstrative, they are yet very
suggestive, and will be of interest here.
If it is true that plants lose little moisture except through
their breathing pores, and if these are closed during those times
when there is not sufficient light to allow carbonic acid gas to be
decomposed by the plant, then during the night, and perhaps,
also, during cloudy weather, plants should lose but little moisture
through their surfaces. To test this question, one of the small
cylinders in the plant -house, containing four fully grown stalks
of maize, was hung upon the scales, to be weighed hourly dur-
ing the day ; and by the side of it was set a Piche evapo-
rometer having an evaporation surface of 27 square inches, also
to be read hourly. Below are given the results of these obser-
vations :
During the day, from 8:15 a. m. until 6:15 P. M., it was some-
what cloudy most of the time, but the clouds were not heavy, and
there was a little sunshine through a haze from 11:15 a. m. until
2:15 p. M. From 8:15 a. m. until 6:15 P. M. the corn and soil
lost 3 pounds of water, and there was evaporated from the evaporo-
meter 31.5 c. e. or 1.2 cu. in. From 6:15 P. M. until 6:45 a. m.
the next morning, the corn had not lost enough to show on the
scales, vrhich are sensitive to one-half pound ; and the evaporo-
meter showed a loss of 2.3 e. c, equal to .14 cu. in. The next
day was bright and sunny the whole time, and from 6:45 a. m.
Transpiration Greatest During Sunshine 45
until 6:15 P. M. the maize lost 7.5 pounds of water and the
evaporometer lost 67.5 c. c, or 4.12 eu. in. ; but during the night
again the loss from the maize was too small to be measured,
while the evaporometer showed a loss of 4.6 c. c, equal to .28
cu. in.
On the next day, Aug. 9, all of the cylinders in the plant-
house were weighed during the forenoon, which was cloudy, but
in the afternoon it cleared and the sun shone brightly. During
the whole of the afternoon and until 9 P. M. we foresd steam from
the boiler, under a pressure of 7 to 15 pounds, into ibe plant-house
through an inch pipe wide open, and iiept ihe house closed
through the experiment. Steam filled the whole plant-house and
condensed upon the glass and walls, dripping in many places from
the roof.
On the following morning, Aug. 10, a number of the cylinders
were again weighed, to see if there had been any loss of water
from the plants, and it was found that three of the small clover
cylinders had lost an average of 2 pounds each, while their mean
loss during the seven preceding days had been at the rate of 2f
pounds. Eight stalks of maize in a large cylinder lost 7 pounds,
while its mean loss per day had been 6f pounds. Six small cylin-
ders, each containing 4 stalks of maize, lost an average of 4f
pounds each, while the mean loss for the week had been 4t
pounds.
It thus appears that during the night and cloudy weather
plants lose but little moisture, but that when the sun shines
brightly, even in an atmosphere nearly saturated with moisture,
there is a very marked loss of water from the gi'owing plants,
and it would appear that the amount is nearly or quite as large
in a damp as in a dry air. These observations seem strange,
and need to be confirmed ; but they are in harmony with our
observations regarding the amount of water required for a pound
of dry matter.
If we bring together all of the observations made in Wiscon-
sin on the amount of water used in the production of dry matter
by plants, they will stand as in the table which follows ;
46 Irrigation and Drainage
Table showing the mean amount of ivater used by various plants in Wisconsin
in producing a ton of dry matter
Water used per ton Dry matter Acre-inches of
No. of *^^ '^''y matter Water used produced water per ton of
trials LBS. inches tons dry matter
Barley.... 5 464.1 20.69 5.05 4.096
Oats 20 503.9 39.53 8.89 4.447
Maize 52 270.9 15.76 6.59 2.391
Clover.... 46 576.6 22.34 4.39 5.089
Peas 1 477.2 16.89 4.009 4.212
Potatoes.. 14 385.1 23.78 6.995 3.399
Total 138 Average 446.3 23.165 5.987 3.939
In computing the results in this table, the combined area of
all cylinders, the combined weights of dry matter produced, and
the combined amounts of water used, have been divided by the
number of trials with each kind of crop and the average results
used in making the calculations.
In considering these results, it should be kept in mind that
the water used by the several crops is made to include that which
was lost through the soil by surface evaporation, because it was
not easy to measure this separately or to prevent it without intro-
ducing abnormal conditions. It is quite certain, however, that
during all of these trials the rate of loss from the- soil has been
somewhat less than would have occurred under the best possible
management with field conditions.
Attention should be called to the fact, also, that the large
amount of water used, averaging for the 138 trials 23.165 inches,
is greater than field conditions would demand, if nothing were
lost by percolation, for the reason that we have planted so as to
utilize less surface area than is the practice in the field ; and it is
to this fact, also, that the very large average yields, when com-
puted per acre, are due, rather than to the growth of plants of
abnormal size.
THE MECHANISM AND METHOD OP TRANSPIRATION
IN PLANTS
Since water plays so large a part in the life and develop-
ment of land plants, and since such large quantities of it are
Mechanism of Transpiration 47
used by them, it will be very helpful to know in what manner
this water is moved through and from the plant, and just what
part it plays in plant life.
We may understand the essentials of this complex process
best if we eompai-e it with our own breathing ; for transpiration
and respiration of land plants have much in common with the
breathing of animals. Both the plant and animal breathe air, and
while breathing it, both give off large quantities of water from the
organs of respiration. If you hold a cold, clean mirror in front
of a person breathing, its surface becomes at once clouded with
the moisture from the breath. So, too, if you hold the same
cold mirror close to the foliage of a growing plant, the moisture
escaping from that will also cloud the mirror.
Now, the primary object of the lungs in our case is not to
retnove water from the system, but to provide a means for oxy-
gen to enter the blood from the air, and for the carbonic acid
gas to escape from the blood into the air. This can take place
rapidly, however, only when the delicate lining of the air cells
in the lungs is kept moist ; and so the chief function of the
water escaping from the lungs is to maintain their inner surface
continually wet. Let the lung lining once become dry, and the
rate at which oxygen could enter and carbonic acid gas escape
from the blood would be so slow that life could not be main-
tained ; and in order that this fatal accident shall not occur, the
lung surface is placed on the inside of the chest, where the rate
of evaporation is very greatly impeded.
When we turn to the breathing of plants, we find that they,
too, are only able to accomplish that very important work as
rapidly as it needs to be done by having a very broad surface
against which the air may come, but so placed that it shall be
kept always wet ; and, just as in our case, it would never do to
have this surface exposed to the open air, so the real breathing
surface of plants is spread out on the inside of their structure,
where hot, strong winds can never reach it.
In Fig. 5 is represented a piece of a barley leaf, partly dis-
sected and much magnified, which shows the breathing surface of
this plant, and how it is protected from excessive evaporation.
48
Irrigation and Drainage
In the upper part of the figure, the under surface of the leaf
is shown covered by its skin or epidermis, through which there
can but little evaporation take place except through the opening
which is shown at sp and the seven others like it ; and even
these openings or breathing
pores are so made that they
may be automatically opened
wide or almost completely
closed when the needs of the
plant call for much or little
air.
In the lower part of the
figure, the skin has been re-
moved from the leaf, so as to
show the actual breathing sur-
face of the barley plant, con-
sisting of the cells marked m,
and which are filled with the
green coloring matter of the
leaf, or chlorophyll. The open
spaces, marked i, between the
breathing cells, are the breath-
ing or respiratory chambers,
which communicate with one
another all through the leaf,
but under the cover of its
skin or epidermis, which in various ways, by a varnish, a wax or
a close mat of hairs, is rendered less pervious to water and
to air. In the case of tall plants, like shrubs and forest
trees, rising a hundred and more feet into the air, nature has
made still greater efforts to avert the danger of plants being
destroyed by the action of drying winds. Here we find the
trunks and all the larger limbs thoroughly protected by a thick
bark, through which there can but little water escape as it slowly
ascends from the roots to the leaves ; indeed, the more detailed
we make the study of the structure and the function of parts in
the plant, the more plain it becomes that in most land plants the
msmm.
Fig. 5. Structure of barley leaf. (After
Sorauer.) «p is a breathing-pore ; m,
cHorophyll cells ; i, respiratory cham-
bers.
Magnitude of Transpiration 49
greatest economy is everywhere practiced in regard to the use of
water.
If it were true that no water need be used by plants except
that which is assimilated during their growth and reproduction, and
in keeping the cells distended and turgid, so that wilting shall
not occur, then there would be little need for irrigation anywhere
except in the most arid of arid regions, for then even the hygro-
scopic moisture of a dry soil would be sufficient in quantity to
supply the demands of almost any land plant.
The facts are, however, that during the hours of sunshine all
growing plants which feed directly upon soil and air must have
their assimilating chlorophyll-bearing cells continually in contact
with a changing volume of air, in order that the carbon, which
makes up so large a part of their dry weight, may be obtained in
sufficient quantity from the carbonic acid gas in the atmosphere.
But the more recent analyses of air show that on the average it
contains but one part of carbonic acid by weight in 2,000 parts.
Now, how much air must a field of clover breath in order that
it may produce two tons of hay per acre ? Let us see.
Boussingault found by analysis that 4,500 pounds of clover
hay harvested from an acre of ground contained no less than 1,680
pounds of carbon, and as this was derived almost wholly from the
carbonic acid of the air, it must have decomposed 6,160 pounds
of carbonic acid in order to procure it. But as there is only
one pound of carbonic acid in 2,000 of air, it follows that
12,320,000 pounds of air must have yielded up the whole of its
carbonic acid gas in order to supply the needed amount of carbon.
Now, one cubic foot of air at a pressure of 29.922 inches and
at a temperature of 62° F. weighs .080728 pounds, and this being
true, not less than 152,600,000 cubic feet of air must have been
required to meet the demands of this clover field for carbonic
acid. This amount of air would cover the acre to a depth of
3,503 feet, having a uniform normal density.
Of course, not all of the carbonic acid in the air which
passes across a clover field can be secured, nor indeed all of
that which enters the intercellular air passages of the green
parts of the plant, and hence it follows that very much larger
D
50 Irrigation and Drainage
volumes of air than have been stated must be brought into close
contact with the growing clover in order to meet its needs. This
air, however, cannot come into intimate relations with the green
chlorophyll-bearing cells of the clover in the field without of
necessity permitting the evaporation of large quantities of water
from the plants ; and this brings us to realize how imperative is
the demand for water by rapidly growing crops.
The writer has found, for example, by direct measurement,
that the air passing three feet above a clover field, and at a
moderate rate, even as early as May 30 in Wisconsin, when the
air temperature is only 52.48° F., may have its relative humidity
increased from 44 to 48 per cent by the moisture taken from the
field ; and this means that 3,510 pounds of water are required to
make even the observed change of humidity in a volume of 152,-
600,000 cu. ft. of air, which is the amount required to carry to
the clover crop its carbon, supposing all the carbon which the air
contained to be utilized. It is quite likely, however, that the
volume of air which did contribute its carbon to Boussingault's
crop of clover not only exceeded fourfold the amount stated
above, but that it also had its relative humidity raised at least
to 94 per cent. If these suppositions are true, then the amount
of water borne away from the plants in question must have ex-
ceeded 176,100 pounds, or at the rate of about 40 pounds of water
for a pound of dry matter ; but it has been shown on a preceding
page that, as a mean of 46 trials, the clover crop did lose from its
tissues and from the soil in which it grew 576.6 pounds of water
per pound of dry matter produced, so that, large as are the
figures stated above, they fall far below the actual ones.
With these estimates and considerations before us, we can
readily understand that one of the chief functions of water in
plant life is to keep the tissues moist and in a suitable condition
to carry on the process of breathing, .whose primary object is to
get the plant its carbon from the air.
In order that the plant may utilize the carbon of the car-
bonic acid in the air, it is necessary that this should come to
the chlorophyll-bearing cells when there is sunshine enough to
decompose it; and since the carbonic acid would be useless at
Control of Transpiration 51
other times, and since the continual ingress and egress of the air
which brings it would entail a steady drain of moisture from the
plant by evaporation, the breathing pores in the leaves are usu-
ally provided with a pair of guard cells, which are so constituted
that they may be opened and closed, and thus exclude nearly all
the air from the interior of the plant ; or, by partly closing
them, to vary the amount of air which may be admitted in a
given time.
In order that the escape of moisture from the plant may be
as little as possible when the breathing pores must be open to
admit air, the great majority of them are placed on the under or
shaded side of the leaf. Thus Goodale, quoting from Weiss,
gives in a table the number of breathing pores observed per
square millimeter of surface on both the under and the upper
surfaces of the leaves of forty species of plants, from which it is
computed that, on the average in these eases, there are 209
breathing pores on the lower side of the leaf for every 51 on the
upper side. How numerous and how minute these openings are
may be appreciated when it is said that in the forty eases cited
there are, on the average, 209,000 stomata on each area the size
of the square in Fig. 6, on the under sides of the leaves of these
species. Taking a specific ease, that of corn, Zea Mays, it is
stated that the breathing pores number, on the under side of the
leaf, 158, and on the upper side 94, or in all 252 for each square
millimeter of leaf, and that the combined area of these openings
is .2124 of a square millimeter, so that 21 per cent of the leaf
surface of corn is made up of doorways through which air may
reach the interior of the plant, and out of which moisture must
escape whenever they are open.
It is not strange, therefore, that large amounts of mois-
ture do escape from plants while they are growing, nor that there
has been provided a means of checking this loss as far as pos-
sible.
The opening and closing of the guard cells is brought about
by changes in the quantity of material which they contain, caus-
ing them to open when tbe cells become distended and to close -
when they again become limp. Unlike the other c^lls in the
52 Irrigation and Drainage
epidermis of the leaf, these guard cells of the breathing pores
contain chlorophyll grains, and are thus able, in the sunshine, to
decompose carbonic acid and carry on the processes of building
plant-food ; but the very fact that food is being elaborated in
these cells causes the sap in them to become more dense, and
this, in its turn, causes water from the direction of the roots to
enter these cells more rapidly than the elaborated materials es-
cape, and so to distend them, and open wide the breathing pores
just at the time when air should be admitted to the interior of
the leaf. But just as soon as the stimulating effect of sunlight
becomes too feeble to allow work to be done in them, then both
on account of the elastic tension of these cell walls and because
of the diminished osmotic pressure toward the guard cells, more
fluid escapes from them than enters them in a given time ; they
become limp, and their concave faces flatten and approach each
other, thus shutting off the entrance of air to the interior of uhe
leaf and at the same time reducing the loss of water to the
mininum.
Again, if the soil moisture becomes insufficient to meet the
demands of the plant, or if hot, drying winds take away the
moisture from the leaves faster than osmotic pressure can supply
it from the roots, then these guard cells are in the very position to
be most and first affected by the shortage of water, and hence are
where they will collapse and check the loss from the leaf surface.
But just as assimilation cannot go on in the absence of sunlight,
so it cannot go on properly in the presence of sunshine if there
is a great deficiency of water; and hence we see that the guard
cells are so conditioned that they will shut off the air from the
interior of the plant at just those times when, if it could be
changing, it would be doing an injury by wasting moisture, which
is so indispensable to growth, and which it is usually really dif-
ficult for plants to get enough of to insure their most rapid and
complete development.
The mechanical principle upon which the guard cells are
opened and closed may be readily understood from Fig. 6. For
simplicity in illustrating the principles, let A, B, C, D represent
four views of a pair of guai'd cells, A being the pair with the
Control of Transpiration
53
mouth open, but with their two ends abutting against each othei'
and pressing tiruily with their backs against the surrounding tis-
sue of the leaf, 3-4 ; B is a cross -section of these cells along the
lO'^OOG
t> 0< )
A C
Fig. 6. Diagram showing the mechanical action of guard cells in opening and
closing breathing poi-es. The square shows the area of under side of leaf
containing an average of 209,000 breathing pores or stomata.
line 1-2 ; while C and D are corresponding views with the breath-
ing pore closed. It will readily be seen that if the water holding
the two cells in A and B rigid and distended partially escapes
from them, their thin walls will then fall down and take the
positions shown in C and D, where, as no displacement can take
place in the directions away from the opening on account of the
surrounding tissue, the walls must advance toward each other,
more or less completely closing the aperture between them, as
shown at C and D. Then, too, when the cells again become dis-
tended and turgid, the pressure will tend to force them to take
the circular outline shown in section at B, and as the back wall
of the two is fixed to the tissue so as not to be able to move,
nearly all of the motion takes place upward and downward, and
this pulls the two faces which are not fixed away from each other
and widens the stoma or pore. It must, of course, be kept in mind
that the shape of the actual guard cells varies in detail in many
ways from the diagram given, and that we have here only intended
to ilhistrate the mechanical principle involved in their opening
and closing.
We see, then, that not only is water a very important sub-
54 Irrigation and Drainage
stance in the economy of plant life, and large quantities of it are
used, but that it is so difficult to alwaj-s procure enough that
nature has provided in the organization of the plant that none
be wasted unnecessarily. It must be very evident, also, that
whatever we may do, in our methods for growing crops, to keep
the plants so fully supplied with moisture that they shall be able
to utilize all the sunlight, — by keeping their breathing pores
wide open, so that all air which can be used will be supplied, —
must tend to give us larger yields.
THE MECHANISM BY WHICH LAND PLANTS SUPPLY
THEMSELVES WITH MOISTURE
So long as plants maintained a simple, or relatively few-celled
structure, and especially so long as they lived wholly or largely
immersed in water, it was an easy matter for them to be supplied
with as much water as they needed by simple diffusion and
osmosis, just as the dry bean, when put to soak, swells and
becomes turgid by the water which has been driven into its cellu-
lar structure under the ceaseless hammering impulses of heat.
But when the time came for plants to abandon the water and to
occupy the land with their varied forms, and especially when that
race began for free air and direct sunshine which led on from
herb to shrub, and through arborescent forms to the giant forest
trees, then it became necessary for that complex and wonderful
system of water-works which, with its intakes in the form of roots,
spread out in a comparatively dry, well-drained soil, is able to
gather from off the damp surfaces of soil grains and send to a
height of a hundred feet a stream which, when diTided between
ten thousand leaves, shall yet have volume and pressure enough
to keep them turgid in a strong, drying wind and a hot sun.
Man, with his mechanical skill and inventive genius, has been
able to install pumping plants which can lift more water to a
greater height in a shorter time ; but to do this he has been
forced to station himself by a running stream, or to import his
energy at a great cost ; while the land plant, independent of wind
Absorbing Surfaces of Boots 55
and water and coal, stations itself in any fertile soil, and does its
work with the warmth of a summer day.
In all our problems of land drainage and irrigation, we are
searching to better understand, and through this better under-
standing to better meet, the conditions under which a system of
roots can best do its work. But the foundation of such an under-
standing should be a knowledge of the root itself, and how it
places itself in the soil in order that it may do its work. Let us
attempt, then, to present in a brief form what has been learned
regarding the essential features of root structure and root action.
Roots have three distinct functions to perform in land plants
having green leaves : first, to absorb moisture and the salts held
in solution ; second, to convey and deliver into the
stem of the plant the water which has been absorbed :
and third, to act as a support to the plant and hold
it upright in the air and sunshine, whenever it is
not trailing or climbing in habit, or is without
stems.
It appears to be the general conviction among
plant physiologists that only the very tip ends of
the roots are particularly serviceable as absorbing
agents, and that even these are serviceable for a
short time only. Farther than this, it is the root-
hairs which branch out in great numbers from them,
rather than the tine roots, which are the real ab- j-. .
sorbing surfaces. These root-hairs are extremely .
delicate, thin-walled tubes, usually not more than of niustai-d
one-eighth of an inch long and a hundredth of an plants,— A with
inch or less in diameter, which stand out on the g ^^i^jj soil^re-
root surfaces like the pile on velvet. These absorb- moved. (After
ing root-hairs never form at the very tip end of a ^^<'^s.)
new advancing root, and as, according to Sachs, they die off
after a few days, they form a brush-like covering on the root
for a distance of half an inch to two or three inches, dying
off behind and forming anew as the advance is made into new
soil. In Fig. 7 are shown the roots of two seedling white mus-
tard plants, A with the particles of soil still adhering to the
56
Irrigation and Drainage
root -hairs and held in a body about the j'oung root, while B is
intended to show the appearance of the plant with the soil grains
washed away. So, too, in Fig. 8 is shown the root of wheat soon
after germination, and again four
weeks later, after the root has ad-
vanced into new soil, and the root-
hairs have died away behind and
new ones formed.
The soil grains of a good soil
are very small, the majority of
them even much less than Too of
an inch in diameter. Indeed, in a
heavj' clay soil one -half of the dry
weight may be made up of soil
grains as small as 25 000 of an inch
in diameter. Now, the fine root-
hairs make their way in between
these minute soil grains, and even
change their shape to fit them-
selves closely upon their surfaces
in many eases.
The soil particles are them-
selves invested with a thin layer
of water, even in the condition
which we know as air-dry, and
as these minute root-hairs apply
themselves closely to the surfaces
of the soil grains, they are brought into immediate contact with
the soil moisture. Indeed, capillarity has the same tendency to
invest the root-hairs with a film of moisture that it has the soil
grains, and we may suppose, in the absence of direct observation,
that the root-hairs all the time carry a film of moisture equal in
thickness to that which invests the soil grains of like diameters,
except in so far as the film of water is thinned out by the flow
through the walls of the root-hairs and away through the root to
meet the demands in the green parts of the plants. Such a thin-
ning out of the film of water on the root-hairs does take place
Fig. 8. Root-hairs of wheat,— A when
verj' young, B four weeks later.
(After Sachs.)
Relation of Root -hairs to Soil Grains
57
so long as they are in action, and it is this very process of thin-
ning whieli furnishes the conditions needed in order to keep them
supplied with water from the surfaces of the soil grains.
The effect of surface tension, as it acts upon the water of a
well-drained soil, is to bring about a certain regularity of dis-
tribution of soil moisture over the surfaces of the soil grains,
which is determined by the sizes of the grains and by the dimen-
sions of the open spaces between them. This condition of things
may be represented by what is shown in Fig. 9 for a particular
soil, in which two root-hairs have found their way in among the
soil grains.
To explain the action of the root, let us suppose that for
some reason there has been no movement of soil moisture and
no root action, so that everything has come to a condition of
rest, and we have what answers to the condition of water
standing in a tank where everything is still and the surface has
become level. We may now suppose that morning has come,
with the sun shining
brightly, so that the
breathing pores in
the green parts of
the plant have opened
wide, making it pos-
sible for both assim-
ilation and evapora-
tion to go on rapidlj'.
Under these condi-
tions the sap in the
tissues of the leaves,
stem and root will
gradually become
more dense than that
which is contained
in the root-hairs, which are encased in the film of soil mois-
ture. But no sooner is this condition of things established than
water in the root-hairs will begin to move toward the root,
stem and leaves more rapidly than the denser sap enters them.
Fig. 9. Distribution of water ou the surfaces of soil
grains and of root hairs, e, main root; 1, air-space;
2, soil grain; 3, tihn of water; hh, root-hairs.
(After Sachs.)
58 Irrigation and Drainage
Just as soon as this happens, however, tlie balance between
the motion inside of the root-hairs and that outside of them will
be destroyed, and then more water will enter the root-hair from
the soil than has been escaping from it into the soil in a unit of
time. This will thin out the film of water which surrounds the
root-hairs, and then water which has been surrovmding the soil
grains, impelled by surface tension, must advance upon the root-
hairs to make good that which has been lost ; and just so long
as the water continues to enter the roots from the root- hairs
faster than osmotic pressure can restore it, just so long will
surface tension force the water from the soil grains upon the
walls of the root-hairs.
Not only will the water which surrounds the soil grains move
toward and upon the root-hairs so long as evaporation is going on
from the plant and assimilation is taking place in its cells, but
with it will go the salts containing potash, nitrogen, phosphorus,
and other ash ingredients of plants, which have been dissolved
by the moisture surrounding the grains.
In the figure the root-hair, h, h, leading out from the main
root, e, is represented, for the sake of clearness, nearly full width
thi'oughout its course, and, as if it had either found or had made
for itself, by setting the soil grains aside, an unobstructed path
in which to develop. As a matter of fact, these root-hairs are
obliged to work their way as best they can between the angles
formed by the meeting of the soil grains, changing both their
direction and their form in order to do so, and sometimes the
spaces are so narrow or the turns so abrupt that the root-hair
seems to have applied itself to the soil, and to have adapted its
shape so as to more completely come in contact with the surface
of the grain itself.
As the water surrounding the soil grains, and which is also
drawn out upon the root-hairs, becomes more and more ex-
hausted, the film finally becomes so thin that the rate at which
the water can be moved out upon the root -hairs is so slow that it
is no longer able to meet the needs of the plant, and it wilts,
and finally ceases to grow altogether.
Attention should be called to the fact that fresh growing
The Extent of Boot Surface 59
roots usually have an acid reaction, and so much so that if they
ai-' allowed to develop in contact with blue litmus paper, it is
changed to red along the lines of contact with the root. Further
than this, if the roots of a plant are allowed to develop in eon-
tact with a polished surface of marble, the lines of root contact
with it will be plainly etched into its surface. Such observations
as these lead to the belief that the delicate root -hairs, at their
innumerable places of contact, hasten the solution of plant-food
from the difficultly soluble ingredients of the soil by the acids
which permeate their walls being exuded upon the soil grains,
and there, in conjunction with the water, being able to dissolve
materials much more rapidly than water alone could do.
When we reflect upon the many wide leaves with which most
land plants are provided, we are impressed with the great extent
of surface through which the sunshine and the air may come into
touch with the plant. But broad as these leaf surfaces are, they
only in the smallest way express the real magnitude of the sur-
face of contact, for the air actually enters the leaf and passes
around and between and in contact with the millions of loosely
packed cells in every leaf, and the number of times the extent of
the internal surface of the leaf exceeds that of its outer sur-
face is more than one would dare to express. Then, too, to in-
crease the contact surface for sunlight, the chlorophyll grains
which are scattered through the interior of the cells around
which the air can pass provide an enormous surface for the
absorption of light.
In the root system under ground, the extremely numerous
root-hairs, small as they are, yet provide a surface for the con-
tact of soil and moisture with the plant which is quite commen-
surate with that furnished by the leaf.
That we may the more clearly appreciate the great need
there is for the vast extent of root surface spread out by agri-
cultural crops, and how important it is that there shall be a
deep, well-drained soil in which the roots may expand, let me
give the measured amounts of water used by four stalks of corn,
and withdrawn by their roots from the soil, between July 29 and
August 11. Two of the maize plants were growing in each of
60
Irrigation and Drainage
two cylinders filled with soil, having a depth of 42 inches and a
diameter of 18 inches. These four stalks of corn, as they were
coming into tassel and their ears were beginning to form, used
during 13 days 150.6 pounds of water, or at the mean rate daily
of 2.896 pounds for each stalk. Had an acre of ground been
planted to corn in rows 3 feet 8 inches each way and four stalks
in a hill, then, with an average consumption of water at the ob-
Pig. 10.
Total root of four stalks of maize, and ot oats, clover and barley.
(Prom "The Soil.")
served rate given above, there would have been withdrawn from
that acre an amount of water, during those 13 days, equal to 244
tons, or 2.42 acre -inches ; and when it is observed that this water
was withdrawn from a soil so dry that no amount of pressure
could express a drop of water from it, it is not strange that such
a mass of roots as those shown in Fig. 10 should be required to
carry away from the soil the water absorbed by the root -hairs as
The Extent of Boot Surface
61
rapidly as it was needed. In reflecting npon the extent of root
surface indicated by the photo-engraving, let it be remembered
that no root-hairs contribute to the mass of the bundle, and that
only a part of the roots proper are there, for many of the smaller
fibers were unavoidably broken off during the operation of wash-
ing away the soil.
Referring, now, to Fig. 11, it will be seen how completelj- the
W
4fi
F^i
j^B "—•*■■!"
sll
1
« '''•!'
will
?
Fig. 11. Distribiition of com roots in field soil. (From "The Soil.")
whole soil of the field is threaded with roots ; for in both cases
two hills of corn, standing opposite each other in adjacent rows,
are shown, and the roots meet and pass one another between the
hills, and in the younger stage these had already exceeded a
depth of two feet ; while in the second case, taken just as the
corn was coming into tassel, the roots had descended until at
this time the whole upper three feet of the field soil was so fully
62 Irrigation and Drainage
occupied with corn roots that not a cube of earth one inch on a
side existed in the three feet of depth which was not penetrated
b}' more than one fiber of threadlike size. In many parts of
the soil the roots were much closer together than this.
At the distance apart of planting in the field from which these
roots were taken, there were, in the surface three feet, 40/^ cubic
feet of soil available for each four stalks, so that by multijilying
the 1,728 cubic inches in one cubic foot by 40%, the number of
cubic feet of soil occupied, we get a total of 69,696 cubic inches.
If, then, each cubic inch of this soil contained not less than one
linear inch of thread-like root, their aggregate length could not
be less than one-twelfth of 69,696, or 5,808 feet, which is 1.1
miles. But this extent of root-surface does not even express the
amount of that to which the root -hairs, which are the real absorb-
ing surfaces, are attached ; and hence we must understand that
the actual area of surface of root-hairs for a full-grown hill of
corn is very much greater than would be indicated by the figures
given above.
Let the reader bear in mind that the corn roots here under
consideration grew in the field under perfectly natural conditions,
and that the cage of wire shown in the engraving was simply
slipped over the block of soil which contained the roots there
shown, after the corn had reached that stage of maturity.
It should also be understood that the four stalks of corn which
absorbed from the soil the 150.6 pounds of water in 13 days did
it at the stage of growth represented by the oldest plants in
Fig. 11 ; and further, that these were only good average plants,
such as would make a yield of 4.5 tons of dry matter per acre.
It may be difficult for some persons to realize how it is
possible for the delicate roots of plants to force their way
through the soil to depths such as are indicated by the engrav-
ings above, especially when the subsoil is a stiff, heavy clay, as
it -was in this case. Nature's method of overcoming the diffi-
culty, however, is simple enough when we come to understand it,
and it is as effective as it is simple.
The first fact which we need to understand when we wish to
learn how a root advances through the soil, is that the soil grains
Hoiv Roots Advance in Soil 63
in the upper four to six feet are never everywhere in close con-
tact with one another. There are great numbers of empty spaces
all through the surface layers of earth, and we get a very forcible
illustration of this fact in setting fence posts. Here we dig a
moderate sized post hole, 2 or 2%^ feet deep, place a 6-inch post in
the hole, and then scrape and ram into the same hole all of the
dirt which was removed from it, and if the job is well done we
have a scant supply to fill it. It is the existence of these unoccu-
pied cavities in the soil which enables roots to make their way
through it by wedging it aside. In a thoroughly puddled soil it
is impossible for roots to develop, not simply for lack of air, but
because there is no room into which it is possible to set the soil
aside to make place for the root. When a fine-grained soil is
thoroughly puddled, all of the small clusters of grains which in a
soil in good tilth hold together, are completely broken down, and
the smallest particles are packed in between the larger ones until
its cavities are so completely obliterated that even water will
not penetrate it ; and when this is true there is not even room for
the root-hairs to make their way between the angles formed by
the soil-grains, for the finest silt and clay particles have been
forced into these to fill them up.
The second fact needed to understand how the root advances
itself in the soil is, that it makes use of osmotic pressure to set
the soil grains aside. Most of us know with what force dry wood
will expand when it becomes wet and is allowed to swell. Iron
hoops are burst by the pressure developed. A primitive method
of blasting rock was to drive dry blocks of wood into the holes
and then wet them. Another method of blasting is to fill the
drill holes with unslaked lime and then add water to slake it. In
all of these cases, the work is done by osmotic pressure, and
the results illustrate how very great this force is when it is
restrained, and how thoroughly adequate it would be for the pur-
poses of the root in setting aside the soil particles if it could make
use of it.
The method by which the root uses osmotic pressure in mak-
ing its way through the soil may be explained with the aid of
Fig. 12, which represents diagrammatieally the tip of an advancing
64
Irrigation and Drainage
root in the soil. It has been found that a short way back from the
tip end of a growing root, there is at 1 a center of growth, where
new cells are developed by repeated enlargements and divisions.
On the forward or advancing side of this center the new cells
form the root-cap, which in the figure is represented by the cells
with heavier lines ; while
-— ^-^ _^ ';- those forming on the rear
^ side of the center are fin-
ally transformed into the
various structures which
constitute the body of the
root proper.
The root -cap is a sort
of shield or thimble, under
the protection of which the
root advances to set aside
the soil grains, and the
method of advance is this :
At the center of growth,
new cells are forming and
enlarging out of the as-
similated products which
are being brought down
from the geeen parts of the plants by osmotic pressure. But
when this strong pressure drives the sap into the forming cells,
they must enlarge just as the dry wood swells, and in doing so
something must give way. As the body of the root is larger than
the tip, and as it is already anchored to the soil by the root-hairs
and any branches which may have formed, the direction of least
resistance is forward, and the cells which are in the interior of
the base of the root-cap are crowded forward and the walls of the
cap are wedged outward so that the soil grains on all sides are
displaced, making room for the end of the root proper to be built
into it. The root-cap does not slide forward through the soil,
shoving past the soil grains, but its outer and rear cells hold
firmly against the earth as the root builds past them, and as fast
as they have performed their function they die and new ones are
it.-^
Fig. 12. Method by which root-hairs advance
through the soil. (Adapted from Sachs.)
How Roots Advance in Soil 65
formed in advance. The root-cap, then, is a sort of point
thi'ough which the root advances, and which is being continually
replaced by a new growth.
The increase of the root in diameter thro-ughout its length is
produced by the addition of new cells wholly within those which
lie in contact with the soil, and the same osmotic pressure is the
power which is exerted outward on all sides to move the earth
away and give room for the increase in size.
Since this osmotic pressure in the roots of plants may be very
great, certainly more than 100 pounds to the square inch, and
presumably several times this amount, and since during the
growth of the root the pressure is increased slowly, and acts
gradually to set the soil aside, it is not difficult to see that the
plant has chosen a method of making its way through the soil
which is not only effective, but one which utilizes the energy and
the materials present in a soil during the growing season with
which to accomplish its purpose. The molecules of soil moisture
are at once the hammer and the wedge, which are driven by soil
temperature into the growing cells to expand them and set the
soil aside.
Part I
IRRIGATION CULTURE
CHAPTER I
THE EXTENT AND GEOGRAPHIC RANGE OF
IRRIGATION
While there is no reason to snppose that the rais-
ingj of crops by irrigation on an extended scale is as
old as agriculture itself, the methods have, nevertheless,
been so long practiced as to far antedate authentic his-
tory. We are told that "the numerous remains of
huge tanks, dams, canals, aqueducts, pipes and pumps
in Egypt, Assyria, Mesopotamia, India, Cejdon, PhcB-
nicia, and Italy, prove that the ancients had a far
more perfect knowledge of hydraulic science than most
people are inclined to credit them with."
In a paper read before the Royal Society of New
South Wales in 1887, Mr. Frederick S. Gipps states
that the first artificial lake or reservoir of which we
have authentic record was Lake Maeris, constructed,
some historians affirm, by King Maeris, and others by
King Amenemhet III, in the twelfth dynasty, 2084
B, C. Its object, it is thought, was the regulation of
(66)
Anfiquif;/ of Irrigation 67
the iuimdatious of the Nile, with which it communi-
cated through a caual 12 miles long and 50 feet broad.
When the river rose to a height of 24 feet, and was
likely to be disastrous to crops, the sluices were opened
and the river relieved by sending the flood into this
lake, which modern travelers give a circumference of
50 miles ; but at times of low water, when drought
was threatened, the gates could be opened and the
volume of the stream reinforced by the water stored
in this reservoir.
Sesostris, who reigned in Egypt in 1491 B. C, is
said to have had a great number of canals cut for the
purposes of trade and irrigation, and to have designed
the first canal to connect the Red Sea with the Medi-
terranean, which was continued by Darius but aban-
doned bjr him, and ultimately completed under the
Ptolemies. So numerous are the irrigation canals of
Egypt that it is estimated that not more than one-
tenth of the water which enters Egypt by the Nile
finds its way into the Mediterranean Sea. Fig. 13
shows Lower Egj-pt, with its extended system of canals
as they exist to-daj'.
The Assyrians appear to have been equally re-
nowned with the Egyptains, from very ancient times,
for their skill and ingenuity in developing extended
irrigation systems, which converted the naturally ster-
ile valleys of the Euphrates and Tigris into the most
fertile of fields. We are told that the country below
Hit, on the Euphrates, and Samarra, on the Tigris,
was at one time intersected with numerous canals, one
of the most ancient of which was the Nahr Malikah,
68
Irrigation and Drainage
connecting the Euphrates with the Tigris. The an-
cient city of Babylon seems to have been protected
from the floods of June, Jnlv and August by high
■—— ' ■■'■ -Jgnuit tBli
Fig. 13. Egyptian system of irrigation canals at the present time. (Willcoeks.)
cemented brick embankments on both banks of the
Euphrates, and, to supplement the protection of these,
and to store water for irrigation, a large reservoir was
excavated 42 miles in circumference and 35 feet deep,
into which the whole river might be turned through
an artificial canal. There were five principal canals
supplied by the Euphrates — the Nahr Malikah, the
Nah-raga, the Nahr Sares. the Kutha, and the Palla-
copus ; while the Tigris furnished water for the great
Antiquity of Irrigation 69
Nahrawan and Dyiel, besides several smaller ones.
Alontj the banks of the former of these canals fed by
the Tigris are now found the ruins of numerous towns
and cities on both sides, which are silent witnesses of
the great importance it held, and the great antiquity
of the work. It started on the right bank of the river,
where it comes from the Hamrine Hills, and was led
away at a distance of six or seven miles from the
stream toward Samarra, where it joined a second
canal. Another feeder was received 10 miles farther
on its course to Bagdad, a few miles beyond which its
waters fell into the river Shirwan, and were again
taken out over a wier and led on through Kurzistan.
It absorbed all the streams from the Sour and Buck-
haree Mountains, and finally discharged into Kerkha
River, but onl}- after having attained a length exceed-
ing 400 miles, with a width varying from 250 to 400
feet. This great canal, with its numerous branches on
either side, leading water to broad irrigated fields,
while it bore along its main waterway the commerce
of those far distant days, stands out as a piece of bold
engineering hardly equaled by anything of its kind in
modern times.
The Phoenicians, in the time of their zenith, were
celebrated for their canals, used both for irrigation
and cit}^ purposes ; and at the time of the invasion of
Africa the Syracusan General Agathocles wrote that
"the African shore was covered with gardens and large
plantations everywhere abounding in canals, by means
of which they were plentifully watered ; " and 50 years
later, when the Romans invaded the Carthaginian do-
70 Irrigation and Drainage
minions, their historian, Polybius, drew a similar pic-
ture of the high state of cultivation of this country.
In the earh- days of both Grecian and Roman his-
tory, great progress had already been made by these
peoples in handling and conveying water by gravity
over long distances for domestic purposes. At Patara
the Greeks, according to Herodotus, carried an aque-
duct across a ravine 200 feet wide and 250 feet deep,
constructing a pipe line by drilling 13 -inch holes
through cubic blocks 3 feet in diameter, fitting these
blocks together with curved necks and recesses, whose
joints were laid in cement and held secure by means
of iron bands run with lead. This was an inverted
syphon, now so often used to cross a ravine or canon
in the west, but made from stone instead of steel
or redwood hooped with steel, so commonly used to-
day.
Rome was supplied with water in Nero's time by
nine separate aqueducts aggregating a length of 255
miles, and which delivered daily 173,000,000 gallons
of water, which was later increased to 312,500,000 gal-
lons. The Aqua Martia conduit, which brought the
drinking water for the city, had a diameter of 16 feet,
and was 40 miles long.
When the Romans invaded France, they constructed
great systems of water works for cities in various
places — at Lyons, Sony, Xisines, Frejus, and Metz.
The Nismes conduit was constructed at the time of
Augustus, 19 B.C., and delivered 14,000,000 gallons
per day. It is noted for the great Pont du Gard,
which carried it across a ravine, and which is spoken
Antiquity of Jrri</(ifioii 71
of by Humble as one of the grandest monuments the
Romans left in France.
China, like Egypt, dates its early enterprises of irri-
gation and transportation by water far back in antiq-
uity, for she has numerous canals, some of them
the most stupendous works of the kind ever under-
taken. The Great Imperial Canal has a length of 650
miles, and connects the Hoang-Ho with the Yang-tse-
Kiang. It has a depth seldom exceeding 5 to 6 feet,
and in it the water moves at the rate of 2% miles per
hour. In its path there are several large lakes, and
across these the canal is carried on the crest of enor-
mous dykes.
If we leave the Old World and come to the New for
records of an early development of the cultivation of
land by irrigation, we shall not be disappointed, for
traces of an earl^- civilization in Colorado, New Mexico
and Arizona, and extending through Mexico and Cen-
tral America on into Peru, are found in the ruins of
ancient towns and irrigating canals in many places.
When the Spaniards invaded Mexico, Central America
and Peru, they were greatly surprised to find in these
countries, and particularly in Peru, the land of the
Incas, verj- elaborate and extensive irrigation systems,
laid out and in actual general use by these people.
Prescott, in his "Conquest of Peru," speaking of
the use of water for irrigation, writes that water "was
conveyed by means of canals and subterraneous aque-
ducts executed on a noble scale. They consisted of
large slabs of freestone nicely fitted together without
cement, and discharged a volume of water sufficient,
72 Irrigation and Drainage
by means of latent ducts or sluices, to moisten the
lands in the lower levels through which they passed.
Some of these aqueducts were of great length. One,
that traversed the district of Condesuyos, measured
between 400 and 500 miles. They were brought from
some lake or natural reservoir in the heart of the
mountains, and were fed at intervals by other basins
which lay in their route along the slopes of the Sierra.
In their descent a passage was sometimes opened
through rocks, and this without the aid of iron tools ;
impracticable mountains were to be turned, rivers and
marshes to be crossed — in short, the same obstacles
were to be encountered as in the construction of their
mighty roads."
THE EXTENT OF IRRIGATION
From what has been said regarding the antiquity of irriga-
tion, we shall not be surprised to find that its practice has found
a geographic range which is commensurate with its distribution
in time. We look tirst to European countries, and begin with
Italy, where irrigation certainly had a vevy earlj- development,
and has ever since been yearly practiced in rural life.
In the valley of the Po, naturally very fertile, but made more
so by thorough and systematic irrigation, water is extensively
applied to almost all crops. To convey some idea of the general
practice of irrigation in the Po valley, it may be stated that on
August 7, 1895, while riding by rail from Turin to Milan, between
Chivasso and Santhia, a distance of 18.5 miles, the writer saw
water being applied to 100 different fields of maize by as many
different parties, and the fields ranged in size all the way from 4
to 20 acres. Wheat, barley, hemp, rye-grass, clover, rice, and
maize are among the field crops generally and extensively irri-
gated in this part of Italy. So, too, very extensive mulberry
Extent of Irrigation 73
orchards are grown for the feeding of silk worms, and these are
set along the main and distributing canals, while the space be-
tween them is occupied by various kinds of farm crops.
In Sicily and throughout southern Italy, nearly all fruit cul-
ture is carried on by irrigation, the ratio of irrigated to non-
irrigated orchards being as 15 to 1, and it is said that 100 10 -year-
old lemon trees, when irrigated, have yielded, on the average,
15,000 lemons, while similar orchards under similar conditions,
but not watered, yield, on the average, but 10,000, or one-third
less per annum. In Lombardy, there were under irrigation, in
1878, 2,034,000 acres; in Piedmont, 1,329,000 acres; in Venetia,
Emilia, and other provinces, enough to make a total of 4,715,000
acres.
In Spain, irrigation is widely practiced, and has been at least
since Roman and Moorish times, and the total acreage has been
variously estimated at from 700,000 to 6,000,000, the first figure
referring to cereals, vegetables and fruits, and the latter to forage
plants and grass lands also. In the last edition of the Encyclo-
pedia Britaunica, the area under irrigation is placed at 2,840,-
160 acres.
In Prance, irrigation began at an early date, and in recent
years new interest has beeji taken in the subject, so much so that
in Consul-General Eathbone's "Eeport on Canals and Irrigation,
1891," it is stated that during the past ten yeai'S in the Depart-
ments Drome, Alpes Maritimes, Aude and Herault, Vaucluse,
Basses-Alpes, Hautes-Alpes, and Loire, 41,460,000 francs were
expended on no less than 13 different canals for waterways and
irrigation.
The Forez Canal,* supplied by the Loire River, and irrigating,
it is said, 65,000 acres, was begun in 1863, and the national gov-
ernment granted $122,200 for it, loaning the balance needed to the
department at 4 per cent. In 1886 there were 23,000 acres served
with 115 miles of ditches, at a cost of $9.50 per acre. The water
is distributed periodically, through pipes carrying it to points
most convenient for a group of farms, where it is delivered to the
♦"Report ou Irrigation," to Senate. Ex. Doe. 41, Part 1, 1892.
74
Irrigation and Drainage
farm laterals. The water is served once each week, on the same
day and hour, the amount received being regulated by the amount
purchased. The delivery commences on land farthest from the
main canal, and each proprietor turns off the water from his lat-
eral when he has received the amount paid for, and the next in
order is then served. The assessment is made out by November
1, and each irrigator is notified of the days and hours when water
will be applied to his land. This irrigation is used almost wholly
on meadows, and it is stated that the value of land has increased
Fig. 14.
Alpine water-meiidows on the south side of the
Simplon Pass, Switzerland.
from $44 to $300 per acre since the development of the irrigation
facilities.
In Switzerland, the mountain streams and rills are used in
very many places on meadows, and this has been done so long and
continuously on some meadows that very decided ridges have been
formed from the sediment moved by the water; and we were sur-
prised to find that, even so high up as the south side of the Sim-
plon Pass, meadows are regulai-ly irrigated, even by the waters
Irrigation in Europe 75
which have come down from the perennial snow fields of still
higher altitudes, as shown in Fig. 14.
In Belgium there is a network of canals known as de la Cam-
pine, which have an aggregate length of 350 miles, constructed
both for navigation and irrigation purposes, at a cost placed at
$5,000,000. This water is generally used in the irrigation of
meadow lands, and the soil of the section is very sandy. It is
even said to have been wholly unproductive until it was reclaimed
by irrigation.
The figures given by E. Laveleye will show the effect of irri-
gation on this land. An area of 5,636 acres of barren soil, pro-
ducing absolutely nothing before irrigation, now yields an average
of 1.32 tons of hay per acre for the first crop, and the aftermath
is counted worth a third as much, making the total equivalent to a
crop of 1.76 tons per acre.
In Denmark, too, an extensive system of 145 canals, carrying,
in 1890, 22,000 second-feet of water, has been provided, whose
object is to reclaim some of the sandy heath lands in Jutland ;
and it is said that the 21,000 acres of land which has been
brought under cultivation has increased in value at the rate of
nearly $80 per acre.
In .Austria-Hungary, irrigation, largely meadow, is practiced
in the Mattig valley, in upper Austria ; in lower Austria ; near
Klagenfurth, in Carinthia ; in certain of the upper and central
valleys in Tyrol ; in the Bistritz valley, and in the valley of the
Elbe, in Bohemia. In these countries the water is usually taken
from rivers, creeks, springs, and ponds, or reservoirs constructed
to impound that which is running to waste, and is led directly
upon the laud by gravity, being taken from the natural channels
by damming the stream until head enough has been secured to
cause the water to discharge into the distributing canal or ditch.
For the irrigation of small meadows, water wheels are found
along the streams in many places, for lifting the water out of the
channels where it runs too low to be led out in the usual manner.
These wheels, provided with buckets, according to Consul -General
Goldschmidt, are found in great numbers on the Eisack River, in
Tyrol, above Bozen. About the large cities, small gardens are
76
Irrigation and Drainage
irrigated by pumps, worked usually by horse -power, taking water
from wells or cisterns. In the mountainous portions of the Tyrol,
meadow irrigation is said to be both very extensive and very
ancient, and in recent times many of the old works have been
reconstructed and new ones introduced.
So, too, in parts of Bavaria, meadow irrigation is common,
and at Baiersdorf, on the river Regnitz, the writer counted, in
MB^^^f iOTMJUuyJ|J| 1 r^''"SI^' -^i^.A'-i
'.JttfZ.^,.-^-^^rA.jJ^
mm
fi^:§W^'-M
Kg. 15. Wheel for lifting water, at Baiersdorf, Bavaria.
1895, no less than 20 of the wheels represented in Fig. 15 in a
distance of 1/^ miles, all of them used in lifting water for meadow
irrigation, the grass being cut and fed to the cows green.
Even in England, there are numerous water-meadows which
have been irrigated so long that the time at which they were laid
out, and the canals and ditches dug, is unknown. It is thought
that some of the English water-meadows were constructed under
the direction of Roman engineering skill, while others have sup-
Irrigation in Europe 77
posed that, they were introduced from the Netherlands ; but the
fact that the character of the works bears a much closer resem-
blance to the Italian construction, and that extensive tracts of
irrigated land are found in the vicinity of ancient Roman stations,
as at Cirencester, lends support to the former view.
This water-meadow irrigation of England is largely confined
to the southern parts of the island, as in Berkshire, along the
Kennet ; in Derbyshire, in the valley of the Dove ; in Dorset ; in
Gloucestershire, along the Churn, Severn, Avon, Lidden, and other
streams ; on the Avon, Itehen, and Test, in Hampshire ; in Wilt-
shire ; in Worcestershire and in Devonshire, where catch meadows
Fig. 16. River and eaual for water-meadow irrigation, at Salisbury, England.
are laid out in the valleys of many rivers and brooks. In Figs.
16 and 17 are shown two views of water-meadow construction at
Salisbury, in England.
If we pass to the continent of Asia, we shall find irrigation
practiced over a wide extent of territory in many countries, but
nowhere on so large a scale as in the ancient and modern develop-
ments in India. How wide the extent of irrigation is in India
may be most easily comprehended from the map. Fig. 18, where,
from Lahore, in the northwest, to Calcutta, in the southeast, a
distance of nearly 1,400 miles, and covering a mean width not less
than 100 miles, a large share of the land is under irrigation.
Other modern irrigation works are to be found at Cuttack, on the
78
Irrigation and Drainage
Mahanadi Eiver, and farther south, at various points in the Madras
Presidency. On the western side of the peninsula, too, back from
Bombay, both at Poona, in the valley of the Mutha River, and at
Fig. 17. Ridged sui-lace of a water-meadow, Salisbury, Englaad.
Bhutan, where there is a great dam 4,067 feet long and 130 feet
high, which forms a reservoir for the supply of the Nira canals,
are other extensive modern irrigation systems. The Vir weir, at
the head of the Nira canal, is 2,340 feet long, with a maximum
height above the river bed of 40 feet, and over this weir, at maxi-
mum flood, there pours 160,000 cubic feet of water per second, in
a sheet 8 feet deep over the crest.
The number of wells used for irrigation in the Madras Presi-
dency has been estimated at not less than 400,000, while the area
they serve is placed at 2,000,000 acres. It is further estimated for
the whole Indian peninsula, British and native, that not less than
300,000 shallow wells are in use, while they serve certainly more
than 6,000,000 acres of land.
Referring, now, more particularly to the extent of ii'rigation
enterpi'ises in India, we learn from Richard J. Hinton's report to
the Senate that in the Madras Presidency, with a population of
80 Irrigation and Drainage
over 31,000,000, the irrigation works, up to 1890, involved an
invested sum amounting to $32,488,000, and the acreage watered
in 1889-90 is placed at 6,000,000. In lower Bengal, the same
year, 5G0,000 acres were under cultivation by irrigation ; while in
the Soane Circle system, 2,611,000 acres were served, 1,305,000 of
which produced rice.
The Gauges system is among the greatest in India. The
Upper Ganges has 890 miles of main canals, with 3,700 distribu-
taries and 17 great dams, and serves 1,205,000 acres, the system
costing $14,6-14,000. The lower Ganges embraces 531 miles of
maiu canal and 1,854 distributaries, serving 620,000 acres, and
costing $7,000,000.
In the Bombay Presidency, in 1889-90, 839,000 acres were
irrigated, and 915,000 acres were under the public canals, whose
total cost is placed at $10,792,000.
In the Punjab and Sind, many ancient works dating from the
twelfth and thirteenth centuries are still in partial operation, but
the great famine years of 1831-32 have brought about many
changes and great improvements. The West Jumna canal had
cost, up to 1890, $8,000,000, and it embraces 84 miles of main
canal and 1,110 miles of distributaries, or 1,194 in all. This,
with the East Jumna canal, controlled 2,000,000 acres, and
brought the Indian Government in 1889 90 a revenue or land
tax of $96,000,000. To this same system belongs the Doab canal,
running parallel with the Jumna river through 450 miles, and
with its 1,112 miles of distributai'ies and 130 miles of main
canals, serving 580,000 acres of land which can be cultivated. It
is said that the total exj^enditure in these provinces for irrigation
purposes is represented by $36,400,000, covering about 6,000,000
acres, one -half of which is under irrigation each year. It is
further represented that for 60 years these investments of capital
have realized an annual return of 8 per cent.
It is stated that the total expenditure under British direction
in the Punjab, Swat, Sirhind, Sind, and the sub-Himalayan
region, has been not less than $64,000,000, with about 2,500 miles
of canals in operation in 1890. But, besides these, there are in
the same districts many private canals and a very large num-
Irri(j(ifion in Asia 81
ber of wells, which supply from 4,000 to 6,000 gallons each 24
hours.
In the Indus valley, there are many small canals, ranging
from 8 to 16 miles in length, having a sum total of 709 miles,
which supply water to 214,000 acres. Three other important
systems supply 411,000 acres, with a total length of channel
amounting to 1,479 mil^s. The Lahore branch of the Bari-Doab
canal irrigates 523,000 acres, besides supplying the water needed
by 1,352 villages. The cost of these works in 1889-90 had reached
$7,872,000, while the year's net proceeds of the water supply was
$873,000, with an associated expenditure of $288,000.
In the province of Oi'issa, with an area of 24,000 square miles
and a population of 4,250,000, there were, in 1889-90, 511,000
acres of laud under the canal systems, ready for irrigation.
Aside from these Anglo-Indian enterprises to which reference
has been made, Hinton states that the native or independent
states of India comprise two-thirds of the peninsula, and that
their peoples are extensive irrigators. The most advanced of
these states, viewed from the standpoint of agriculture and irri-
gation, is Jaipur, with an area of 14,463 square miles and a
population of 2,500,000. It has 108 separate systems of irrigation
works, with 364 miles of main canals and 422 miles of distribu-
taries. In the native state of Mysore, there are 1,000 miles of
irrigation canals and 20,000 village tanks.
In the island of Ceylon, a decided effort has been and is being
made to restore and to extend the ancient irrigation systems,
which have been allowed to fall into ruin. The British authori-
ties in 1891 had already restored 2,250 of the small and 59 of the
large tanks or reservoirs ; they have constructed 245 wiers and
700 miles of canals. There are now over 5,000 ancient reser-
voirs in the island, and one king, in the twelfth century, is
credited with having had constructed 4,770 tanks and 543 great
canals.
In Australia, work seems to be largely prospective as yet, with
but few results actually attained. But there are some 500,000
acres in Victoria to be served by irrigation works which are in
progress. In New South Wales, the amount of land in 1891
¥
82 Irrigation and Drainage
actually irrigated is said not to exceed 3,000 acres, but provision
is being made under government aid for the irrigation of 38,000
acres. In South Australia, there are about 5,000 acres now under
irrigation, and a company has been organized for the develop-
ment of an irrigation system on the Murray Eiver, to place under
ditch 200,000 acres. Up to June, 1891, the government had sunk
15 artesian wells, 8 of which are flowing and yielding from 8,228
to 3,000,000 gallons in 24 hours. These are in Queensland, and
in the same region there are 86 private artesian flowing wells.
In China, irrigation has a very extended and general distri-
bution. The great canal systems are laid out primarily for
transportation, but are used jointly and generally for irrigation
as well. It is said the most scrupulous care is taken to save and
utilize every source of water in cultivation ; and in southern and
central China it is estimated than an acre of land is made to sup-
port from three to five persons.
In the provinces of Ningpo, Fo-Kien and Shanghai, the water
is generally taken from small ditches led out from the streams or
larger canals, or they are fed from springs in the hilly country.
It is said that in very many parts almost every farm is supplied
from canals or shallow laterals, which are 2 or 3 miles long
and from 10 to 30 feet wide, leading out at right angles from the
main canals, often from 200 to 400 feet apart. It se'ems, from the
written accounts, that a large part of the water used by the gar-
deners, and even on the small but numerous rice fields, is raised
out of the canals and streams or ponds by a species of chain
or rope pump, worked either by hand or by oxen, and in the
irrigation season, when water is needed, they are run at night
as well as day. It is even said that water for irrigating is carried
considerable distances at times and places, in buckets on a yoke
placed on the shoulders of men.
In the province of Fo-Kien, where the rainfall is both quite
large and well distributed, irrigation is still practiced, but as a
means of insuring larger yields rather than a necessity.
In Japan, as well as in China, irrigation is, and has been from
time immemorial, extensively practiced, and it is estimated that not
less than two-thirds of the 12,500,000 acres of land under culti-
Irrigation in Asia 8^
vation, supporting 41,000,000 people, is under irrigation ; that is
to say, water is artificially applied to not less than 8,000,000 acres
of land in Japan.
On the island of Lew Chew, belonging to Japan, the greatest
care is exercised to utilize the water of all the short streams,
wherever they are found. On the slopes and in the narrow val-
leys, the lands are carefully leveled by terracing, to avoid washing
and to cause the water to spread evenly over the surface of the
ground, and thus become most effective. On the margins of the
terraces are slight ridges, which are given permanency of form
by being covered with grass ; these are boundaries and foot -ways,
as well as barriers against land washing. It is said that dams
are not used upon the streams, but in times of high water the
terracing has been such that the water can be at once spread out
over the cultivated areas, and gently let down to the lower levels
and back into the main channels, after having done its work of
saturating and fertilizing the fields. In order that nothing shall
be lost by way of washing, there is a lower waterway around the
margin of the terraced areas, which conducts the water to one
corner, where it passes to the next terrace below, but first flowing
through a sort of settling basin partly filled with vines or rubbish,
whose purpose it is to collect the silt, to be used in compost heaps
for manure. At the lowermost level, before the water finally
enters the stream, there is a larger settling basin, through which
the water must pass and drop whatever of value it may still
be carrying where it may be recovered and used.
In writing of irrigation in Siam, Consul -General Jacob T.
Child states that about one-half of that country is under cultiva-
tion, and of this four-fifths are irrigated, much of it for rice.
The fields are supplied with water from canals, which branch out
from the rivers in all directions, and the main lines are con-
structed by the general government, but those supplying the
individual fields directly are made by the individual land
owners. Where the land is government property, there is an
annual rental of about 28 cents per ri, or 84 cents per acre,
including the use of the water.
Irrigation in other parts of Asia at the present time, as is
84 Irrigation and Drainage
the ease both in Japan and China, is carried on in a small way
largely by individual effort, but is widely and irregularly scattered,
so that it is difficult to form any exact or even adequate estimate
of the extent of such irrigation ; and the same statement is also
true of British India outside of the organized enterprises of
English capital. Indeed, it must be said that all through Asia
Minor and Central Asia isolated and individual irrigation plants
are to be found, which in the aggregate would sum up a grand
total. Irrigation is carried on in this individual way in Corea, in
Afghanistan, and parts of Russian Central Asia. It is even to be
found in Thibet and on the Pamir, "The Eoof of the World,"
12,000 feet above sea level. Nor can it be said that this irriga-
tion is carried on only in those places where water is most easily
obtainable, for it is sometimes secured under conditions so labo-
rious that few Americans would think of undertaking the task. In
parts of Armenia, for example, where underground water is
abundant, and where the ground is sloping, it is a common prac-
tice to dig a line of wells extending down the slope and then, by
connecting the bottoms of these wells by a tunnel leading out
upon the surface at a lower level, the water becomes available for
irrigation, and is collected in reservoirs, to be used as needed.
"Water is thus collected and brought to the surface of the ground
by gravity, even in sections where the uppermost wells must be
sunk to depths as great as 80 to 100 feet. The same practice also
is said to exist in the mountainous parts of Afghanistan, Cashmere,
and other parts of Central Asia, and these underground water
channels are often of considerable length, and many miles in
the aggregate have been constructed.
On the continent of Africa, the most extended system is, of
course, that found in Egypt, developed along the valley and
delta of the Nile. Willcoeks tells us, in his"Egyptain Irriga-
tion," that the cultivated or irrigated area in this long, narrow
valley is 4,955,000 acres, while the total area which is below the
level of flood waters, and, therefore, capable of irrigation, is
6,400,000 acres. This irrigated area is confined at present to a
long and relatively very narrow strip bordering the course of the
stream, and the naked desert sands on both sides come up sharp
Irrigation in Africa 85
against the watered area, which begins at Assuan, some 500 miles
from the sea, not following the windings of the Nile. The popu-
lation of this country is now given as 5,000,000, but it has been
estimated that Egypt once supported 20,000,000 inhabitants ; and
a practice of today, which will seem strange to the reader, is
that of digging up the rubbish piles on the sites of ancient vil-
lages, towns and cities, which represent the waste of the millions
who have passed away, and using this as manure to fertilize the
fields now under irrigation. The dry climate of this country has
preserved these materials from complete decay, and the site of
old Cairo is now being dug over to enrich the fields for miles
around.
The mean daily discharge of water which passes from Upper
Egypt, at Cairo, into Lower Egypt is estimated at 8,830,000,000
cubic feet, but as large as this amount is, it would require 20
days to place Wisconsin under an inch of water.
In the Algerian Sahara, since the sinking of the first artesian
well, in 1848, at Biskra, by M. Henri Fournel, the work went for-
ward, until in 1875 there had been 615 wells put down, having
an average depth of 145 feet, 404 of which are in the province of
Constantine, 194 in the province of Algiers, and 15 in that of
Oran. A strange thing about these artesian waters is the pres-
ence in them of nitrates, and irrigation with them has brought
upon the desert sands wonderful oases, 43 in number in the Oued
Rir, supporting, in 1885, 520,000 date palms of bearing age, 140,-
000 palms from one to seven years old, and about 100,000 other
fruit trees.
On the south side of the equator, in Africa, there has as yet
but little been done in the way of irrigation, although in Cape
Colony efforts are being made. In 1889 the U. S. Consul at Cape
Town, Geo. F. Hollis, states that the most complete storage work
now constructed in the colony, and the most important, is that at
Van Wyck's Vley. The rainfall in this section is very irregular,
the average for 11 years being 10 inches. The reservoir has de-
pended upon a catchment area of, say, 240 square miles, but this
has been found inadequate, and a furrow is now nearly com-
pleted to bring over water from a neighboring river, by which it
86 Irrigation and Braifiage
is estimated that the water- covered area will be increased to 19
square miles, with a depth of 27 feet. The land under irrigation
is owned by the government, and is leased at a minimum rate of
10 shillings per acre.
In the island of Madagascar, on the east, and that of Madeira,
on the west of Africa, irrigation is also practiced ; in the former
for rice culture only, and by the system of flooding ; but in Ma-
deira the system is both elaborate and extensive, covering over
one-half of the whole island, or 120 square miles. There are no
catchment basins or reservoirs other than those which nature has
provided, and the water used is that which the soil collects dur-
ing the rainy season and gives up in the form of springs. The
water carriers have been constructed with care and skill, and
some of them have a length of 60 or 70 miles. The thrifty
farmers have on their lands reservoirs into which they collect
their share of water when it is delivered to them, and from this
distribute it to their several crops as they desire ; but the poorer
class, who cannot afford the reservoir, are obliged to use the water
directly as it comes to them, and as the intervals are long be-
tween the delivery of water they are not able to make the best use
of that which they get, and their crops suffer in consequence.
In the Pacific Ocean, too, there are islands in which irrigation
is practiced with great skill outside of those of Japan, to which
reference has already been made. Among these may be men-
tioned those of Hawaii, and the development of the sugar industry
there has in recent years led to a corresponding development of
the facilities for irrigation, as would be expected when it is stated
that adequate irrigation there has increased the yield of sugar
from 2 tons to 4 tons per acre. It is stated that there are about
90,000 acres under cane, one-half of which is irrigated ; some
7,000 acres of rice, and 5,000 acres of bananas, the rice being all
under water. The water supply comes from mountain streams,
with their reservoirs, and from springs and artesian wells.
The artesian wells about Pearl Harbor are among the largest,
yielding an enormous quantity of water, sufficient to irrigate
20,000 acres of rice and a large area of bananas and other products
besides. There have been 100 of these wells sunk about the mar-
Irrigation in America 87
gin of this island, 21 to 42 feet above ocean level, in the last 12
years, and four of tliem are said to yield water enough for a city
of 165,000 inhabitants.
In the island of Java, too, ii-rigation is extensively practiced,
and regarding the island of Lombock, still to the east of Java,
Mr. Arthur E. Wallace writes : "It was here that I first obtained
an adequate idea of one of the most wonderful systems of cultiva-
tion in the world, equaling all that is related of Chinese industry,
and, as far as I know, surpassing, in the labor bestowed on it,
any tract of equal extent in the most civilized countries of Europe.
I rode through this strange garden utterly amazed, and hardly
able to realize the fact that in this remote and little known island,
Lombock, from which all Europeans (except a few traders at the
port) are jealously excluded, many hundreds of square miles of
irregularly undulating country have been so skillfully terraced and
leveled and permeated by artificial channels that every portion of
it can be irrigated and dried at pleasure."
Passing, now, to the American continent, we have already
referred to its prehistoric irrigation works, and to the extensive
and complete systems of irrigation found in South America before
the occupancy of that continent by the Spanish and Portuguese,
for irrigation was practiced there on both slopes of the great
Andean ranges. It must be said, however, to the shame of our
boasted civilization, that a very large share of those extensive
and valuable impi'ovements have been allowed to pass into ruin,
and now must be restored at great cost.
In the Argentine Republic, lying between 20° and 56° south
latitude, irrigation is being practiced in the provinces of Cordoba,
San Luis, Mendosa, San Juan, Catamarca, Rioja, Santiago del
Estero, Tucman, Salta and Jujuy ; and it is stated that the total
area under cultivation by irrigation will exceed 1,759,600 acres.
According to Consul Baker's report, works were begun about
1882-83 on a number of large dams and canals, using the water
of four important rivers, at an estimated cost of $15,280,000,
which were expected to have an aggregate capacity equal to about
3,020,000 acres.
While there are large areas in the aggregate irrigated in
88 Irrigation and Drainage
other parts of South America, Central Aineriea and Mexico, no
very definite idea of its magnitude or distribution can be given
as yet.
Newell says, in the report of the Eleventh Census, that in
the western part of the United States the area irrigated within the
arid and sub-humid regions aggregated at the end of ilay,
1890, 3,631,381 acres, or 5,674.03 square miles, while the total
number of farms or holdings upon which crops were raised by
irrigation was 54,136. In this irrigation, water was supplied by
3,930 wells to 51,896 acres, at an average cost of $245.58 per well,
the wells yielding an average of 54.43 gallons per minute. The
average value of pi-oduets fi-om this irrigated land per acre he
found to be $14.89, the farms having an estimated mean value
per acre of $83.28, while the average size of each farm or holding
was 67 acres. The average value of the product of the average
farm was thus $897.63.
To bring together in close review the extent of irrigation as
it is today practiced in the various parts of the world, we may
quote the statements of Wilson : " The total area irrigated in
India is about 25,000,000 acres, in Egypt about 6,000,000 acres,
and in Italy about 3,700,000 acres. In Spain there are 500,000
acres, in France 400,000 acres, and in the United States 4,000,000
acres of irrigated land. This means that crops are grown on
40,000,000 acres which, but for irrigation, would be relatively bar-
ren or not profitably productive. In addition to these, there are
some millions more of acres cultivated by aid of irrigation in
China, Japan, Australia, Algeria, South America, and elsewhere."
These figures seem enormous as we read them, and so they
are, but they leave an exaggerated impression on. the mind which
needs to be corrected, for veiy few realize the magnitude of the
volume of water which must be handled in raising a crop by irri-
gation. In order that we may not mislead in this direction, we
wish to make the correction. Let us suppose that the amount of
land which is actually under irrigation at the present time is four
times the 40,000,000 of acres which have been enumerated above.
Now, were this supposition true, and all of these acres were
brought together in one solid square, it would have but 500 miles
Climatic Conditions 89
on a side. But to cover siieh au area as this with 2 inches of
water once in 10 days would require more than three Nile rivers
flowing at maximum flood — a river 50 feet deep, 1.156 miles wide,
running three miles an hour.
THE CLBIATIC CONDITIONS UNDER WHICH IRRIGATION
IS PRACTICED
If we study the eonditious of rainfall under which
irrigation has been practiced, we shall find rather wide
variations in the mean amounts which fall upon the dif-
ferent countries, especially when the mean annual rain-
falls are compared. In all of India except the extreme
northwest part; throughout China, Japan and Siam,
in Italy, and France, and Mexico, as much rain falls
during the year as falls in the United States east of
the 97th meridian, if we except Louisiana, Mississippi,
Georgia and Florida, — an amount ranging from 23.6
inches to 51.2 inches, or between 60 and 130 centime-
ters. But in Asiatic Turkey, Persia, Afghanistan and
the extreme northwest of India ; in the irrigated parts
of Queensland, Victoria and South Australia ; in Cape
Colony, Algiers and Spain ; and in Argentina and the
western United States, south of Washington state, the
rainfall for the year drops from 23 inches to less than
8 inches. On the lower Ganges, from the Soane region
to Calcutta, and south along the east coast as far as the
Orissa canals, the yearly rainfall is equal to that of the
southern states, or from 51 inches to 78 inches (130 to
200 centimeters). It is not, therefore, in regions of
small rainfall alone that irrigation systems have been
developed. Indeed, there must always be contiguous
90 Irrigation and Drainage
territory of considerable rainfall, in order to fill the soil
and give rise to springs, streams, and wells, or there
could be no water for irrigation. It is only the accident
of a great stream like the Nile, gathering its waters in a
region of large rainfall, that makes any irrigation at all
possible in a rainless, desert country like Upper and
Lower Egypt.
The distribution of the rainfall with reference to the
growing season, more than the quantity of it, is the
chief factor in determining whether irrigation will be
profitable or not. In the irrigated districts of Italy,
Spain, France, Austria -Hungary, Algiers, Cape Colony,
Asia Minor, Armenia, Victoria, South Australia, and
the westernmost part of the United States, there is a
tendency to a dry time in early or late summer, at the
time when crops need water most, or in some of these
countries it may be dry the whole season through, the
rainy season being in fall or winter. In China, south-
eru Japan, Siam and Ceylon the summer is rainy, but
there is a tendency to develop a short dry season in
midsummer. In Switzerland, Belgium, Denmark, Eng-
land, Bavaria, Madagascar, North Japan, Queensland,
and Mexico there is usually a uniform distribution of
rain throughout the whole of the growing season. In
these latter countries, however, while irrigation is prac-
ticed in them, it must be said that it is supplementary
rather than a necessity.
CHAPTER II
THE CONDITIONS WHICH MAKE IRRIGATION IMPERA-
TIVE, DESIRABLE OR UNNECESSARY
To uuderstand the conditions which make it im-
perative, desirable or unnecessary to irrigate land, it
is important to have clearly in mind the various objects
which may be attained by the application of water to
cultivated fields.
THE OBJECTS OP IRRIGATION
The first and primary object to be attained in irri-
gating the soils of arid climates is to establish those
moisture relations which are essential to plant growth,
and the same fundamental object will usually stand
first in sub -humid climates, as it may even in those
which are distinctly humid ; for in the sub -humid
climates it very often happens that the intervals
between rains of sufficient quantity are so long that
almost any crop may suffer ; and in humid climates
there are certain crops, like the cranberry and rice,
which profit by more or less protracted inundations ;
or, again, like the pineapple, growing upon extremely
leachy sands, which can retain but a small quantity
of water even for a single day, and where it is neces-
(91)
92 Irrigation and Drainage
sary that even frequent showers shall be supplemented
in order that the best results may be attained.
In the second place, lands may be irrigated in any
climate, when it is desired to carry to the land ferti-
lizing matter which the irrigation waters may hold in
solution or in suspension. The extreme cases of this
practice are where cultivators take advantage of the
large amounts of plant -food which are borne along
in the waters of streams into which the sewage of
great cities, like Paris or Edinburgh, are discharged.
Such waters are extremely fertile, even when much
diluted. In emphasis of this fact. Fig. 19 shows a"
field of heavy grass growing on the Craigentinny
meadows of Edinburgh. This ground yields from three
to five such crops each year, and has done so for
nearh' a century, with no other fertilization than that
which comes to it through the winter and summer
application of diluted sewage water. Hence we need
not be surprised that such lands have rented as high
as 18 to 22 pounds sterling for the season per acre,
when the rentals are sold at auction to the highest
bidder.
But ordinary river waters are widely used in vari-
ous countries, chiefly for the fertilization of water
meadows. The amount of water applied in a year
is in some sections very great, reaching, in the Vosges,
in France, over 300 feet in depth per year. It is
during the colder portions of the year, when the grass
is not growing, that the larger part of the water is
applied, depending upon the absorptive and retentive
power of the soil to abstract from the water, as it
Objects of Irrigation
93
passes over and leaohes through, enough of potash,
phosphoric apid, and other ingredients of plant-food,
to hold the strength of the soil up to a uniformly high
standard, even when constant cropping is practiced.
Pig. 19. Heavy growth of grass on the Craigentinny meadows,
Edinburgh, Scotland.
A third object in irrigation, in certain classes of
cases, is primarily to change the texture of the soil.
When soils are very sandy and open, having so small
a water capacity that not enough is retained for the
growth of most crops, then the leading of the water of
a turbid stream over such lands results in the deposition
of silt to such an extent as, in the course of time, to
94 Irrigation and Drainage
veiy materially improve their phj'Sical condition ; but
at the same time giving to these soils a large amount
of plant -food, for the material borne along in suspen-
sion in the water of rivers is usually very valuable,
derived, as it is, from the finest and best parts of fer-
tile soils. These ingredients of the flood waters of
the river Nile are extremely valuable to those desei't
sands which, under the long action of strong winds,
have lost the major part of those fine and extremely
important grains which the sand storms of the deserts
have picked up and swept awaj'.
In the fourth type of uTigation, which is an extreme
case of the last, the aim is to flood low tracts of land
with silt -bearing water in large volume, and to hold it
there until the suspended matters have been deposited,
so as ultimately to build up the whole tract, raising it to
a level at which it may be naturally drained, or at which
a depth of fertile soil sufiicient to meet the needs of
agriculture may be laid down over one which had been
undesirable. Low -Mug lands have been built up by
this method until in the course of ten or a dozen years
the whole surface has been raised as much as 5 to 7 feet.
A fifth type of irrigation, which has i-eceived a
notable expansion in recent years, has for its primary
object the rapid destruction of the organic matters held
in solution and in suspension in the sewage waters of
cities, in order that they shall reach river channels and
the ground -water of the surrounding country suffi-
ciently purified not to endanger the public health by
a pollution of drinking waters, or by developing un-
heal thful atmospheric conditions.
Water Needed for a Paying Crop 95
THE LEAST AMOUNT OF WATER WHICH CAN PRODUCE
A PAYING CROP
In the manufacture of butter from milk, it is a mat-
ter of prime commercial importance to know just how
much butter -fat that milk contains, and what is the
maximum amount of butter that fat is capable of pro-
ducing ; for only this knowledge can show how closely
the manufacturer is working to his possible limit of
profit, and how great his losses may be. For a like rea-
son, it is very important to know what is the minimum
amount of water which, under stated climatic conditions,
can meet the needs of a given crop, producing a paying
yield. It is important, because only such knowledge as
this can show how economical or how wasteful our
methods of tillage may be, and how nearly we are realiz-
ing the largest profits which are possible to the business.
In the Introduction, much pains has been taken
to give in detail the evidence, and the methods of pro-
curing it, which shows how much water must be used
by a given crop in coming to maturity when placed
under the best of conditions. This has been done,
because it is a part of the knowledge which is needed
to show under what climatic conditions irrigation maj'',
and under what it may not, be practiced ; because it
is needed to show how far into the sub -humid districts
agricultural operations may be pushed without the aid
of irrigation ; because it will help to teach how far we
may hope, by the practice of the best methods of till-
age, to dispense with irrigation, and avert disastrous
results during seasons of drought.
96 Irrigation and Drainage
"We have already referred at some length to the
seemingly small amounts of water used by the wheat
crop in coming to maturity in the San Joaquin valley,
in California, and to the long period of some 60 days
at the close of its growing season during which it
receives no water, either as rain or by irrigation.
What is the minimum amount of water which is capa-
ble of producing a yield of 15, 20, 30 or 40 bushels of
wheat per acre, and how does this compare with the
actual raipfall of the San Joaquin valley '?
We have made no observations with wheat, like those
which have been recorded for oats, barley, maize, clover
and potatoes, but from similar observations made by
Hellriegel, in Germany, it is probable that the amount
of water necessaiy to produce a ton of dry matter with
wheat is not very far from 906,000 pounds or 453 tons,
equal to 3.998 acre -inches. How many bushels of
wheat should this give '?
The ratio of the dry weight of the kernels to that
of the straw and chaff in a crop of wheat has been
found to be as 1 to 1.1 in a dry season, but to be as
high as 1 to 1.5 when there has not been an undesir-
able stimulation to the growth of straw. But where
wheat is irrigated in the southeast of France, Gasparin
states that a ratio of 1 of grain to 2 of straw is usual.
If we take the ratio of 1 to 1.5, and allow 60 pounds
to the bushel of wheat, we maj^ compute the least
amount of water which is likely to enable a crop of
varying yields per acre to be produced, and the re-
sults of such a computation are given in the following
table :
Water Needed for a Given Crop 97
Table showing the least amount of water required to produce different yields of
wheat per acre %vhen the ratio of grain to straw is 1-1.5
Yield
per acre
Wgt
;. of grain
Wgt. of straw
Total wgt.
Water used
No.
bushels
TONS
TONS
TONS
ACRE-IN.
15
.45
.675
1.125
4.498
20
.6
.9
1.5
5.998
25
.75
1.125
1.875
7.497
30
.9
1.35
2.25
8.997
35
1.05
1.575
2.625
10.495
40
1.2
1.8
3
12
These amouuts of water, given in the last column
of the table, are so small that they appear false, for the
quantity given for 15 bushels to the acre is almost
covered by the rainfall of the most arid parts of the
world. Several statements need to be made in order
to put them in their true light.
In the first place, the figures could only be true
when the amount and kind of plant -food in the soil
is all that the crop can use to advantage, for no amount
of pure water can make up for such deficiencies except
in so far as it makes more rapid the solution of other-
wise unavailable plant -food in the soil. Then, again,
the data for the table were procured under conditions
which permitted no loss of moisture from the soil,
either by surface drainage or by downward movements
beyond the depth of root action. Further than this,
no account is taken of the water which may have been
given to the soil in bringing it to the proper moisture
conditions previous to planting the crop in it. Water
enough was given to the soil to put it in the right
condition to start with, and the amounts in the table
98 Irrigation and Drainage
cover simply what has been found necessary to main-
tain that amount against surface evaporation from the
soil under the best of conditions and through the crop
itself. In the San Joaquin valley there is a long inter-
val, from the end of July until the fall rains begin
in November, when some evaporation is taking place
from the surface soil, and enough rain must have
fallen to bring the soil up to a good standard condi-
tion of soil moisture before the crop is started in it,
and the amounts in the table would need to be in-
creased by so much, at least, as would be required
to establish this condition.
How much water would need to be added to the
soil in the San Joaquin valley by the fall rains, in
order to restore the proper amount of soil water, or
how great the evaporation may be between harvest and
seeding time, we do not know. We do know, however,
that the rate of evaporation from the surface of a diy
soil is not very rapid. In illustration of this, it may
be stated that after removing a crop of oats from four
of our cj'linders in the field, a record was kept of the
loss of moistui-e from them between Aug. 2 and Aug.
25, and it was found that the total evaporation from
7.068 square feet was 5.3 pounds. In another case,
six cylinders in the field lost by surface evaporation
between Jan. 10, 1894, and March 12, 41.8 pounds.
The loss per 100 days expressed in inches in the first
ease was .6268, and in the second 1.243.
Taking the first of these two figures, which is likely
to be more nearly true for the district in question, the
total loss would be .79 inches, and at the second rate
Water Needed for a Given Crop 99
it would be 1.54 inches. It is certain that there is a
further loss from these soils which is likely to be
nearl}' if not quite as large as that computed, and that
is the evaporation which takes place through the grain
after coming to maturity, while it is standing upon the
ground before being cut ; for it is known that the
movement of water through the plant does not stop at
once when the kernels have fully matured. Further
than this, if a considerable time intervenes between
the time of the first rains and the germination of the
seed, and especially if, after the grain comes up, it
for any reason makes an abnormally' slow growth, there
will then be considerable additional losses which are
not included in the figures given in the table ; and it
would seem that the average necessary loss of soil
moisture from these lands which in no way contributes
to the growth of the crop of wheat may easily be as
high as 3 inches. If this be true, the figures in the
last column of the table would be nearer 7.5, 9, 10.5,
12, 13.5 and 15 inches, respectively, for the differ-
ent yields, than those stated. It is further probable
that for the lighter yields, where the grain would have
to stand thinner on the ground or else the plants be
smaller, there would be absolutely more loss of water
from the surface of the soil itself, and, hence, that the
lower figures just given are likely to be found larger
than they are there stated.
The mean annual rainfall of the San Joaquin-
Sacramento valley, as given by Harrington in his rain-
fall map, ranges from 5 inches in the far south to 12
inches in the north, this amount all falling between
100 Irrigation and Drainage
November 1 and May 1. The tenth census gives the
average yield of wheat per acre as 6 to 13 bushels in
the south, and fi-om 13 to 20 bushels in the northern
part of the valley. The average yield in California
in 1879, on 1,832,429 acres, is placed at 16.1 bushels
per acre ; while it is stated that certified records of
yields as high as 73 bushels per acre are recorded from
areas as large as 10 acres.
If we consider the "diy farming" sections of the
state of Washington, where most of the wheat gi-own
has been the spring varieties, sown in April, and some-
times as late as May, and harvested in August or early
September, we shall have the growing season more
nearly the same as that in the corresponding latitudes of
the humid parts of the United States. Here, too,
the rainfall in amount is very nearly the same as that of
the district to the south for the corresponding period of
time, but the rains begin a month earlier and continue a
month later, so that the amount for the year is from 8.4
to 13.5 inches, or about 33 per cent more, while the
mean yield per acre was 23.4 bushels in 1879, as
against 16.1 bushels in California. There is here
in Washington, as in California, a dry period of
some 60 days, in which the crop is forced to come to
maturity.
It appears, therefore, fi'om the observations and
experiments regarding the number of inches of water
which may be used in producing a ton of dry matter,
and from practical experience in ai'id climates, that on
deep, fertile soils, well managed, good, paying yields of
wheat may be realized where the amount of rain is as
Like Rainfalls not Equally Productive 101
small as 7 or 8 iuclies, and large yields when it reaches
12 to 15 inches, provided it has a suitable distribu-
tion.
LIKE AMOUNTS OF RAINFALL NOT EQUALLY
PRODUCTIVE
In the United States west of the 97th meridian,
where the rainfall is notably deficient, except on the
west side of the Cascade range in Oregon and Washing-
ton, there are a large number of areas in which an effort
has been made to grow crops of one kind or another
without irrigation, and in considerable areas with
marked success, as in the San Joaquin-Sacramento val-
ley, in California, and in eastern Washington and
Oregon, to which reference has just been made. In the
sketch map. Fig. 20, prepared by Newell, the areas in
which "di*y farming," or farming without irrigation,
has been practiced with greater or less success, are
represented in black. It will be seen that this map
shows a long, continuous area, just west of the 97th
meridian, another one in California, and a third in
Washington, besides very many smaller ones. These
three larger areas receive very nearly the same amounts
of rainfall for the year, but the distribution of it in time
is very different. In California the rain all falls in [the
six months, November to April, inclusive ; in Washing-
ton it is from October to May, inclusive, while in the
97th meridian region, much the larger part of the rain
falls during the months between April and September.
The eastern region, therefore, has its moisture well dis-
102
Irrigation and Drainage
Fig. 20. The dry-farming areas (in black) in the western United States.
(After Xewell.)
tributed through the growing season, while both of the
western areas mature their crops in from 30 to 60 days
of continuous nearly rainless weather ; and yet, if we
Lil-e Rainfalls not Equally Productive 103
compare the yields of barley, oats, rye and wheat in
the three districts, taking the Tenth Census figures for
California, Washington and Kansas for comparison,
the yields are largest in Washington and smallest in
Kansas, as shown below:
, Mean yield per acre of .
Barley Oats Rye Wheat
Washington .38 41 14 23
California 21 26.8 9 16.1
Kansas 12.5 19 12 9.3
Expressing these differences in percentages, we get:
Washington 100 100 100 100
California 55.2 65.3 64.3 70
Kansas 32.9 46.3 85.7 40.4
As the soils in the three regions are notably fertile,
and were in 1879 very close, on the average, to virgin
conditions, the differences in yield can hardly be attrib-
uted to differences in plant -food other than as influenced
by soil moisture ; and as the quantity of rain which falls
in Kansas during the growing season, April to Septem-
ber, inclusive, is 11.5 to 16.8 inches, while that in
Washington is only 8.4 to 13.5 inches, it appears plain
that in some waj' the available moisture is more effective
on the Pacific border than it is in the 97th meridian
region.
It would be of very great practical importance to
understand fully the causes which permit so small an
amount of rain as that of eastern Washington, falling,
so much of it, before the growing season, to ensure the
104 Irrigation and Drainage
maturity of such large crops under so clear a skj'' and in
spite of so long and continuous a period of di'ought,
while in western Kansas 25 to 38 per cent more rain-
fall, well distributed through the growing season, pro-
duces less than one -half the yield per acre. The yield
is certainly less than one-half, because the averages
used for Kansas are too large for the western section
of the state, whose rainfall has been brought into
comparison.
While we are a long way from possessing the need-
ful data for the solution of this problem, some of the
factors are evident enough, and may be stated here. In
the first place, the rains of the sections of California and
of Washington under consideration fall in the cooler
portion of the year, when the air is more nearly
saturated and when the wind velocities are small,
while the sun is much of the time obscured bj^ clouds.
All these conditions conspire to permit a large per
cent of the water which falls upon the ground to
enter it deeply, without being lost by evaporation,
while a deep, retentive soil serves to prevent loss by
drainage.
In western Kansas, on the other hand, where the
rain falls largeh' in the form of showers in the heated,
sunny season of the year, and where the wind veloci-
ties are high and the air extremely dry, it is plain that
a much larger per cent of water falling as rain must
be at once lost by evaporation from the surface of the
soil, before it has had an opportunity to enter it deeply
enough to be retained by soil mulches.
In the second place, a frequent surface wetting of
lATce Rainfalls not Equally Productive 105
the soil, such as takes place in Kansas, tends strongly
to hold the roots near to the surface, where with scanty
mulches they are certain to suffer severely whenever a
period of ten days without rain occurs ; and if, under
these conditions, the plant is able to send new roots
more deeply into the soil, they can find there but a
scanty supply of moisture, because there have been no
winter rains sufficient to produce percolation. Then,
again, after such a ten -day drought, with the surface
roots now become inactive through a dying off of the
absorbing root -hairs, when the next rain does fall,
unless it is a very heavy one, the major part of it will
be lost by evaporation from the soil, in the case of
crops like wheat, oats, rye and barley, long before the
plants are able to put themselves in position to take
full advantage of it.
In California and eastern Washington, the case is
radically different. There the water gets well into the
soil before the crop is put upon the ground. Moisture
enough is present to produce germination, and the
roots develop at first near the surface, when there is
ample moisture present ; but later, under the rainless
conditions, it is quite likely that they advance more
and more deeply into the ground as the moisture in
the upper layers of the soil becomes too scanty, and
thus day by day the effectiveness of the soil -mulch is
increased, while the roots have only to advance so far
as is needful to allow capillarity to bring them the
water they need from the store which the soil has re-
tained. With these physical principles and conditions
set down as foot -lights to illuminate our problem, and
106 Irrigation and Drainage
with the other fact for a side-light turned upon it,
that 6 inches of water, when the crop can have it to
use to the best advantage, is enough to produce 20
bushels of wheat to the acre, we can see its outlines
with sufficient clearness to feel sure that more study
in the field would give us its full solution. As the
matter now stands, the case is sufficientlj^ clear that
we may not conclude, because 9 to 12 inches of rain
in California has produced abundant crops of wheat,
that a similar rainfall in the sub -humid belt ought
to produce like results. It should be sufficiently
evident, also, that even with the best modes of till-
age we can hope to adopt, there will still be much
more water required per pound of dry matter pro-
duced all through the sub -humid region, than is de-
manded under the conditions of the lower San Joa-
quin vallej'.
The same principles make it very clear, also, that a
judicious application of water by the methods of irri-
gation, in many humid climates, is certain to be at-
tended by marked increase in the yield.
FREQUENCY AND LENGTH OF PERIODS OF
DROUGHT
In humid and sub-humid regions, it is the frequent recur-
rence of periods of small or no rainfall, especially if they occur
at the time when the crop is approaching or has reached the
fruiting stage, that, more than anything else, makes extremely
careful and thorough tillage, or else supplementary irrigation,
indispensable, if large yields are to be realized.
In our repeated trials in the field cylinders here in Wiscon-
Frequency and Length of Drought 107
sin, we have found it necessary to water all of the crops grown
in them as often as once in seven days; and even this period has
been found too long for the soils which are coarse and sandy.
So, too, in our field irrigation we have found that as much as 2
inches of water may be applied to corn, cabbages and potatoes as
often as once in 10 days, with decided advantage unless, in the
interval, there has been a rain of from .5 to a full inch, falling
nearly at one time, so as to penetrate the ground deeply. To
what extent and to what advantage tillage may take the place of
irrigation, or make it undesirable, we shall discuss in the next
chapter. Starting with the soil well supplied with moisture at
seeding time, and then a uniform distribution of rains equal to 1
inch once in seven days through the growing season, we shall have
all the moisture that would be needed for very large crops. On
the average of years most parts of the United States east of the
97th meridian have this amount of rain during the growing season.
It is true, however, that in many parts of the hiimid districts the
distribution of the rainfall in time and in quantity is such as to
cause severe suffering from drought.
To show just why it is that in Wisconsin the irrigation of
ordinary farm crops does produce a very marked increase in the
yield, we have made a study of the distribution of the rainfall at
Madison for the years 1887 to 1897, inclusive. The results
are here given in a condensed form, as an illustration of the type
of rainfall conditions under which, in a humid climate, it may be
desirable to irrigate where water privileges are such as to permit
it to be done cheaply.
It is generally true that a rain of .05 or even of .1 of an
inch, when it comes alone, separated by two or three days
from any other rain, benefits ordinary farm crops but little ; but
in order that we shall not undervalue the rain which falls, we
have included everything, large and small alike, and have con-
structed a table for these years, 1887 to 1897, which shows the
length and number of periods in each year between April 1 and
September 30, when there were consecutive days having a rain-
fall whose sum did not exceed .05, .1, .5, 1, 1.5, 2, and 2.5
inches. The table is given below:
108 Irrigaiion and Drainage
Table showing the number of periods, and the mean length of these periods, in each
year when the amount of rain is not greater than that given at the head of the
respective columns
Rainfall Rainfall Rainfall Rainfall Rainfall Rainfall Rainfall
of .05 in. of .1 in. of .5 in. of 1 in. of 1.5 in. of 2 in. of 2.5 in.
period
Av. No.
periods 23.27
Studying this table, it will be seen that during the eleven
years there have been on the average in the growing season 23
periods of 5.82 days' duration when the rainfall has not exceeded
.05 inches ; there have been 23 periods 6 days long, with a rain-
fall of .1 inch ; 19 periods on the average 9 days long, with a
rainfall of .5 inch ; 15 periods each year 12 days long, with 1
inch ; 12 periods 16 days each, with but 1.5 inches ; 10 periods
each season 19 days long, with 2 inches, and 8 periods each
season of 25 days each, when the mean rainfall did not exceed
2.5 inches.
If we will now compare the field yields which are produced
under these conditions of rainfall, we shall be better able to see
how important are the quantity and time distribution of rain. It
Frequency and Length of Drought 109
is unfortunate that wo are unable to present closely comparable
data for more than the years 1894, '95, '96 and '97, and even for
these years only for corn. As for other crops in the different
years, they were grown on different soils ; but bringing the yields
of dry matter of maize per acre into comparison with the rainfall
conditions under which they were produced, we shall have the
table which follows :
Table showing the relation of yields of dry matter per acre to the quantity and
distribution of rainfall
Yield of dry-
matter per acre Aggregate No. of inches of rainfall
.05
.1
.5
1
1.5
2
2.5
20
18
16
15
13
9
9
7
7
9
12
14
14
20
21
23
13
9
5
5
4
6
7
14
20
37
39
44
27
27
27
26
19
15
11
4
5
6
7
10
12
17
28
28
19
15
11
8
6
5
5
9
13
17
23
31
Year Periods tons
ion, / No. of rainfall periods
I Length days
1895 |f°-°* :! !! . 1.401
L Length
'" {Zt '■'■ ■■ " "«^
If the rainfall in 1896 and in 1894 is compared with that in
1895, when there was a very much smaller crop, it will be seen
that the number of rainfall periods in 1895 is decidedly less, while
the length of them is much greater. It was this much longer
interval of time intervening between like quantities of rain which
determined the small yield ; and it is this character of the rain
of humid climates which so seriously cuts down the average
yields per acre, and which makes it possible for the methods of
irrigation to give such constant and such large yields wherever it
is well practiced in arid climates.
Taking the best year of the four, 1896, it will be seen that
the average length of periods of 1 inch of rainfall was 7 days,
and there were 26 of them in the six months, making about as
uniform distribution of rain as is likely to occur in humid cli-
mates ; but there were in this season 1 period of 10 days, 3
periods of 11 days, 2 periods of 12 days and 2 periods of 13 days'
duration with but 1 inch of rain, which are too long in Wisconsin
110 Irrigation and Drainage
to permit the largest crops the soil is capable of carrying. This
statement is founded upon the fact that with plenty of water the
same soils did produce much larger crops, the differences being
such as are given in the table below:
Table showing differences in yield when the natural rainfall in Wisconsin is
supplemented by irrigation
Yields per acre
Corn Potatoes Strawberries Cabbage Barley Clover
^ ^ ^;^. A ^ A 'A ^ "i^. ^ ^ A ^
TONS TONS BU. BU. BOXES BOXES TONS TONS BU. BU. TONS TONS
1894 5.176 3.835 6,867 3,496
1895 5.293 1.384 8,732 1,030 51 25 4.01 1.45
1896 5.15 4.145 394.2 290.5 22.79 20.04 3.632 2.254
1897 4.252 3.405 333.9 212.3 45.67 44.25 4.434 2.482
These figures show very clearly the insufficiency of rain in
these four years to produce the largest possible yields, and they
show to what extent irrigation in a climate such as that which
has occurred during the years 1894 to 1897 in Wisconsin is likely
to increase the average yields.
CONDITIONS WHICH MODIFY THE EFFECTIVENESS OP
RAINFALL
The rains which fall upon a given area are not equally effec-
tive under all conditions of soil and topogi'aphy, and hence it
happens that irrigation may be desirable in localities where the
amount of rain which falls may be both large and uniformly dis-
tributed throughout the growing season. It has been pointed out,
in the study aiming to measure the amount of water required to
produce a pound of dry matter, that it was necessary to water the
sandy soils of coarse texture once in three to four days in order
Conditions Modifying Effectiveness of Rainfall 111
to prevent the crops from suffering for lack of moisture, while
once in seven days met the needs of plants growing upon soils
of the finer texture used in the experiments.
The difficulty in the case of soils of coarse texture is, not
that the water evaporates more rapidly from the surface of them,
nor is it because more water must be present in them in order
that plants may utilize it, for it is true that the surface evapora-
tion from them is slower than with most other soils, and that
plants may use the water more closely from them than is
possible when the grains are smaller. The real trouble is found
in the fact that when they are underlaid by a coarse subsoil, and
when standing water in the ground is more than 5 feet below
the surface, the water drains out so completely in a short time
that not enough remains to keep the crop from wilting.
We do not yet know how closely the water may be used up
in field soils of different textures before crops of different kinds
will begin to suffer, or will have their rate of growth cheeked ;
but the writer has found that clover, timothy, blue -grass and
maize have their growth brought nearly to a standstill in a clay
loam soil underlaid with sand at 3 to 4 feet, when the amount of
water left in it was that stated in the table below:
Table shoiving the arnoxint of water in a clay loam in the field when crops wilted
and growth
was brought nearly
to a standstill
Clover
Timothy and
Blue-grass
Maize
Depth of
sample
PER CENT
PER CENT
PER CENT
0- 6 inches loam
8.39
6.55
6.97
C-12
clay loam
8.48
7.62
7.8
12-18
clay
12.42
11.49
n.e
18-24 "
clay
13.27
13.58
11.98
24-30
clay
13.52
13.26
10.84
40-43 "
sand
9.53
18.37
4.17
Nothing more definite can be said regarding the data of this
table, than that under the moisture relations there shown, growth
was practically at a standstill, and that when very considerably
larger percentages of water were present in the soil the normal
rate of growth was checked.
112
Irrigation and Drainage
How completely water will drain out of sands by percolation
under conditions in which almost no evaporation can take place, is
shown by the data in the table which follows, in which the results
were obtained by a set of apparatus shown in Fig. 21. It will be
-^p—| —-(V— (— u—
DOrCLLSli
11
i
p5l
m
m
] t^s^^s^m^
Fig. 21. Method of determining water-holding power of long columns of sand.
seen that the conditions provided by the apparatus are such that
standing water was maintained continuously in the soil at a level
of 8 feet below the surface, and, hence, that the amount of water
retained in the whole column was much greater than it would
have been were it under such field conditions as when standing
Water Lost by Percolation
113
water in the ground is found at greater distances below the sur-
face :
Table showitig the per cent of water in 8-foot columns of sand after percolation
periods of different lengths
Effective diameter of sand
grains
474 mm. .185 mm
. .155 mm.
.1143 mm.
.0826 mm,
Height of sec'n
above ground
water
Water retained after percolating over 2 :
years
INCHES FEET
PER CENT
PER CENT
PER CENT
PER CENT
PER CENT
96 .... 93
.27
.17
.22
1.26
3.44
93 .... 90
8
.22
.17
.23
1.16
3.44
90 .... 87
.23
.16
.29
1.34
3.82
87 .... 84
.22
.15
.32
1.61
3.83
84 .... 81
.23
.18
.61
1.98
'3.93
81 .... 78
7
.29
.19
1.07
2.32
4.19
78 .... 75
.44
.26
1.33
2.61
4.38
75 .... 72
.89
.58
1.57
2.90
4.92
72 .... 69
1.18
1.16
1.80
3.12
4.94
69 .... 66
6
1.48
1.45
1.85
3.36
5.70
66 .... 63
1.71
1.67
2.03
3.56
5.91
63 .... 60
1.80
1.80
2.18
3.92
6.43
60 .... 57
1.83
1.86
2.26
4.22
6.77
57 .... 54
5
1.93
1.87
2.27
4.53
7.72
54 .... 51
1.98
1.98
2.30
4.88
8.59
51 .... 48
2.02
1.92
2.38
5.42
9.42
48 .... 45
2.03
2.12
2.46
6.03
10.50
45 .... 42
4
2.02
2.07
2.71
6.99
11.34
42 .... 39
2.06
2.18
3.08
7.47
12.58
39 .... 36
2.17
2.29
3.46
8.71
13
36 .... 33
2.31
2.48
4.10
10.54
14.95
33 .... 30
3
2.36
2.65
5.09
11.77
15.90
30 .... 27
2.63
3.14
6.36
12.95
17.20
27 .... 24
2.86
3.63
8.74
15.05
17.96
24 .... 21
3.42
4.71
13.52
17.24
18.92
21 .... 18
2
4.26
6.76
23.57
19.08
20.49
18 .... 15
6.41
9.38
27.93
19.37
21.34
15 .... 12
9.77
14.66
23.61
21.44
21.63
12 .... 9
16.08
21.31
22.46
22.69
22.68
9 .... 6
1
19.33
22.39
22 76
23.20
23.39
6 .... 3
20.96
23.52
22.88
24.22
30.28
3 ....
21.58
24.61
23.54
25.07
24.06
H
114 Irrigation and Drainage
. , fgms. 2,1214 2,474.9 3,515. 4,576.2 5,831.5
Total ^vater retained.... I p^^^^^^ ^^ 5^,5 ^25 9.41 11.82
Water retained after 4 fgms. 3,128. 3,551.1 4,259.9 5,672. 6,659.7
days t per cent 6.25 7.238 8.785 11.66 13.5
Water retained after 9 fgms. 2,926. 3,213.5 4,094.7 5,416.2 6,452.8
days Ipercent 5.846 6.753 8.445 11.13 13.08
fgms. 10,425.2 10,356.2 10,329.1 10,289.7 10,606.8
Total water recovered... I p^^^^^^ 20.84 21.12 21.3 21.15 21.5
Totalweightof dry sand... gms. 50,050. 49,060. 48,490. 48,650. 49,340.
A glance at this table shows how completely and how rapidly
water will drain away by downward percolation from the coarse
and fine sands when there is nothing within 8 feet of the surface
to prevent it. It will be seen that in four days the coarsest sand
had lost nearly three-quarters of all the water it could contain
under flooded conditions, while the finest had lost nearly one-
half ; and this has occurred, too, under such conditions that
standing water is maintained within 8 feet of the surface. Had
standing water been 16 feet from the surface, it is quite likely
that the surface 8 feet of these sands would not have retained 3
per cent in the coarsest sample nor 5 per cent in the finest.
With such a rate of loss of water from sands as this, it must
be plain that the coarser soils, when they are long distances from
standing water in the ground, or are not underlaid with a more
impervious stratum near the surface, must lose the water which
falls upon them as rain so rapidly that even in very humid regions
they cannot maintain profitable crops without irrigation.
It is this fact of coarse texture, coupled with the long inter-
vals of deficient rain, more than a lack of plant-food, which has
maintained in an unproductive state the extensive areas of sandy
lands found in Minnesota, Wisconsin, Michigan, New York, New
Jersey, and further south, in the United states, and throughout
Belgium, Holland, and the plains of northern Germany, in
Europe. Had the soils of these areas identically the same
chemical composition, but a texture as fine as that of our best
soils, so that water would drain from them no more rapidly,
profitable agriculture could be practiced upon them under the
rainfall conditions which exist. And it is possible to so supple-
Water Lost by Surface Drainage 115
ment the rainfall upon these types of land by irrigation as, even
with the coarse texture they have, to make them bear remuner-
ative crops of various kinds, as has been abundantly proved in
many places.
Passing from the extreme type of "barrens" soil which we
have been discussing, there are extremely large areas of only the
less coarse loamy sands and sandy loams in all humid climates,
where supplementary irrigation, could it be pi'acticed, would
greatly increase the average yields beyond the largest which are
possible with the best of tillage ; but the truth of this proposition
does not carry with it the corollary that it will pay to irrigate
them whenever there is an abundance of water to do so.
Then, there are topographic conditions which greatly diminish
the effectiveness of the rain which may fall in a given locality.
When the fields are decidedly rolling, every one is familiar with
the fact that wherever heavy rains occur in short periods of time
very considerable percentages of such rains flow at once over the
surface to the lower lying lands, producing only damaging effects
upon the hillsides. Under such conditions, it is plain that the
measured rainfall of the growing season is not available for crop
production, even though the texture of the soil were such as to
retain the whole of it, could it rest upon the surface long enough
to be absorbed. Further than this, the brows of hills, where
they are exposed to the prevailing winds, lose a much higher
percentage of the absorbed soil moisture by surface evaporation than
is the case on the level plains or in the sheltered valleys, and
from this it follows that when the whole rainfall of the growing
season is only enough to make the soil produce at its full
capacity, the exposed hillsides must receive irrigation sufficient
to make good the losses by surface drainage and greater evapo-
ration, if equally large yields per acre are expected.
Again, in rolling countries, where the higher lands are
porous, the rains which are there lost by deep percolation reap-
pear under the lower lands, to supplement the rain which falls
directly there, and often to such an extent as to make under-
draining a necessity. Where these conditions exist, and where
drainage is sufficient, so that crops may take advantage of the
116 Irrigation and Drainage
underflow which gives rise to a natural sub -irrigation, it is evi-
dent that on such lands a much smaller rainfall, and even longer
intervals between rains, may occur without producing suffering
from drought.
From what has been shown regarding the amount of water
used by different crops in coming to maturity, it is plain that
with a full command of water for irrigation, it would be possible
for crops to be grown on a given soil in a given locality when the
natural rainfall would not permit that crop to be so grown. It
is plain, therefore, that neither the amount of rain nor the dis-
tribution of it are sufficient to determine under what conditions
irrigation will or will not pay.
CHAPTER III
THE EXTENT TO WHICH TILLAGE MAY TAKE THE
PLACE OF BAIN OB IBBIGATION
Were it desirable to irrigate all agricultural lands
lying in humid climates, it would not be possible to
do so, on account of the insufficiency of water for the
purpose. The truth of this proposition will be evident
if we deal quantitatively with the problem.
THE INSUFFICIENCY OF WATER TO IRRIGATE ALL
CULTIVATED LANDS
Humphreys and Abbott have placed the mean an-
nual discharge of the Mississippi at 19,500,000,000,000
cubic feet, while the catchment area is placed at 1,-
244,000 square miles. Assuming that these quantities
are correct, then the mean annual run -off for the
whole Mississippi basin would be 6.747 inches. But
not all this run -off is available for irrigation, were it
desirable to so use it ; for during a large part of the
time this water is flowing away when the season does
not permit of its being used, and it is impracticable to
impound it and hold it until it might be used. If we
take the mean daily discharge of the river as tbt of
its annual amount, and allow that the whole of this is
(117)
118 Irrigation and Drainage
available for irrigatiou purposes during the irrigation
season, it is capable- of watering but .092 of the catch-
ment area at the rate of 2 inches of water once in 10
days.
It is true that the mean run-ofif for the whole
basin is less than is found in much of the United
States ; but, taking a district where the mean drainage
to the sea is 30 inches instead of 6.7, and supposing
that this is collected into canals, so as to be used for
irrigation, then it would be able to supply only about
.4 of the area at the rate assumed above. It is
safe to saj^ that these estimates of the area which
might be irrigated with such amounts of water is too
large, for the summer discharge, when irrigation is
needed, is in most drainage basins much less than
the mean values which have been taken in making
the calculations.
Newell has made as close an estimate of the mean
annual run -off for the United States as the then ex-
isting data would permit, and has expressed the
results in a map, which is reproduced in Fig. 22. An
inspection of this map will make it plain, in connec-
tion with what has been said, that however great irri-
gation developments may become in the future, it is
not possible for the practice to be extended so as to
displace the methods of "dry farming." Hence the
question, How far may tillage compensate for a defi-
cient rainfall ? will long remain a pertinent one in
agricultural practice.
Since much less than one -half of agricultural lands
can be irrigated under any efforts which can be made,
120 Irrigation and Drainage
it is plain that the question, What are the largest
possible yields which maj- be realized without irri-
gation ? is of much greater practical moment than its
converse.
THE MOST WHICH MAT BE HOPED FOR TILLAGE
IN THE USE OF WATER
We have, as yet, been unable experimentally to
demonstrate that any method of handling the soil
under field conditions will permit it to abstract from
the air above it an amount of moisture sufficiently
large to materially contribute to the supply already in
the soil, and* thus aid in compensating for a deficient
rainfall. The discussion presented on a preceding
page, regarding the production of wheat in California
and Washington without irrigation, certainly lends no
weight to the view that the hygroscopic power of soils
aids in supplying moisture to the crops under field
conditions. Still, it must be admitted that those who
maintain that soils do absorb important quantities of
moisture from the air direct maj' continue to do so
without fear of successful refutation by existing posi-
tive knowledge.
If it is true that soils do not withdraw from the
air important quantities of water, then the most which
can be hoped for by methods of tillage is that they
may store in the soil and retain there the water which
falls as rain, until that shall be removed by the action
of the roots of the crop growing upon the field. Cer-
tain it is that no method of tillage now practiced can
Amount of Rain Needed 121
very much iuci-ease the moisture in the soil above that
which falls as rain or snow.
Further than this, we have no reason to believe
that mere tillage, as such, can in any way diminish
the rate of transpiration from the crop which is grow-
ing upon the soil being tilled, unless, indeed, it should
be done by root -pruning, a method decidedly injurious
in most cases. It follows, therefore, that in no way
can we hope, by methods of tillage, to diminish the
loss of water by transpiration through the crop itself.
We may, indeed, make the conditions for growth so
favorable that the maximum amount of dry matter is
developed during the time a given amount of water
is being evaporated from the surface of the crop ; but
so far as the direct influence of tillage is concerned, it
can only lessen the evaporation from the soil surface,
and reduce the losses by percolation and by surface
drainage. No amount or kind of tillage can dispense
with water ; that must be had, either from rain or
snow, or be supplied by irrigation. With water enough
iu the soil to make a crop, good tillage will bring the
most out of it ; but when the rainfall has really been
deficient, nothing short of irrigation can make the crop.
AMOUNT OF RAIN NEEDED TO PRODUCE CROPS
IN HUMID AND SUB -HUMID REGIONS
Having pointed out in a general way the limitations of tillage
in conserving soil moisture for crop production, it is important to
show how great its possibilities may be when unaided by irriga-
tion ; for if in humid and sub-humid climates tillage may enable
122 Irrigation and Drainage
all soils to produce maximum crops of all kinds, then irrigation
will be unnecessary in them.
It has been shown that, under conditions in which no water
can be lost by siu-faee or under- drainage:
Clover uses 5.089 acre-inches in producing one ton of dry matter.
Oats " 4.447
Barley " 4.096
Maize " 2.391 " " "
Potatoes use 3.399
These figures are an approximate measure of the demands of
those crops for water, and if one, twc or three tons of dry matter
per acre are to be produced by these crops, then the amount of
available rainfall needed will be given by multiplying the figures
in this table by the yield which is expected per acre from
the soil.
Let us see what the available rainfall is in various parts of
the eastern and central United States. To make the discussion as
pointed as possible, let us draw our data from the states of Illi-
nois, Indiana, Iowa, eastern Kansas, Maine, Michigan, Missouri,
Minnesota, New York, Ohio, Pennsylvania, Vermont, and Wiscon-
sin. In these states, what is the amount of rainfall available for
crop production ?
In the map. Fig. 23, is represented the mean annual rainfall of
the United States, as given by the Weather Bureau. Such a map,
however, does not show the amount of water which is available for
crop production, because, as shown on the map. Fig. 22, a large
part of this rain is carried to the sea in the rivers, and cannot,
therefore, be used in producing crops. But if the rains which
would drain away were subtracted from the mean annual rainfall,
the difference would still be too large, for we have many showers
which are too slight to be of any sei"vice whatever. Not only this,
but very light rains often do positive injury by destroying the
effectiveness of earth mulches which have been developed by till-
age, thus causing a loss of a part of the water already in the soil,
with that which fell as rain.
It is further necessary, in discussing this problem, to consider
124 Irrigation and Drainage
the growing season of the specific crop in question, in ordei' to
know whether tillage alone will answer for that crop, unaided by
irrigation. The first crop of clover, for example, must be largely
made by the rains of May and June in the states which have been
named, while the crop of potatoes will be determined more largely
by that which falls between June and October. The period of
barley would extend from May 1 nearly through July ; oats, from
May to the middle of August ; and maize, from the middle of May
to the middle of September.
In the table which follows, the amount of rain which falls
during the growing season of barley, oats and maize has been
given, and from the averages have been deducted the amounts
which it is quite certain do not become available for crop produe*
tion, on account of loss by drainage and by the light rains not
penetrating deeply enough to be of service agriculturally:
Table shoiving the mean rainfall for the groioing season for barley, oats
and maize Rainfall in inches for
Barley Oats Maize
^inois 13 15 15.25
Indiana 13.5 15.25 16.25
Iowa 12.5 14.25 15.375
Eastern Kansas 12 13.625 14.5
Southern Maine 10.5 12.25 14
Southern Michigan 9.5 11 12.625
Missouri 13.25 15 16.375
Minnesota 10.75 12.25 13.75
New York 10.25 12 13.5
Ohio 11.75 13.5 15
Pennsylvania 12 14 15.75
"Vermont 10.5 12.5 14.75
Wisconsin 11.5 13.25 15
Mean 11.616 13.375 14.779
Estimated loss by percolation and from light showers. 2.964 3.185 2.765
Mean effective rain 8.625 10.19 12.014
In estimating the loss from percolation and small showers, 2
inches has been assumed as the amount of percolation in the case
of barley and oats, and 1.5 inches for maize. The amount deducted
for small, ineffective showers has been gotten by taking the total
Titne Distribution of Rain 125
rainfall for Madison, Wisconsin, from 1887 to 18G7, which was
less than .2 of an inch in any day of 24 hours during the periods
covered by the table.
Now, these amounts of effective rain, could they be used with
the same economy as we were able to use them in our plant cylin-
ders, ought to produce the following yields per acre:
Bu. per acre
Barley 40.29
Oats 64.97
Maize 71.51
In making these calculations, the ratio of grain to straw for
barley has been taken as 2 to 3, and for oats as 1 to 1.448: and
we have used the percentages of water in grain and straw given in
tables of feeding-stuffs. In the ease of maize, data derived from
direct determinations by the writer have been used.
It will be seen that these computed yields, although much
larger than average yields, are, nevertheless, very close to what is
expected during our best seasons, when there has been plenty of
rain, well distributed, and when the crop has not been affected by
disease or insects. It appears, therefore, that the rainfall for the
thirteen states enumerated is sufficient in quantity to produce very
heavy crops, not only of the three grains named, but of many
others also.
THE DISTRIBUTION OP RAIN IN TIME USUALLY UNFA-
VORABLE TO MAXIMUM YIELDS
There is little question that in the thirteeen states named, the
mean yields of barley, oats and maize would easily be held to
41, 64 and 75 bushels per acre respectively, if it were only possible
to control the distribution of rain in time and in quantity, as it is
controlled by irrigation. As it is, however, such large mean
yields can never be reached by tillage alone in a territory as
extended as that under consideration. This will be evident from
the table which follows, in which th» mean yields of barley, oats
126 Irrigation and Drainage
and maize for 1879 are given as reported for the 10th Census for
the thirteen states:
Bu. barley Bu. oats Bu. maize
per acre per acre per acre
Illinois 22.25 32.24 36.12
Indiana 23.35 25.02 31.39
Iowa 20.23 33.57 41.57
Kansas 12.52 18.77 30.93
Maine 21.81 28.76 30.99
Michigan 22.1 33.93 35.3
Missouri 19.01 21.34 36.22
Minnesota 25.62 37.97 33.81
New York 21.85 29.79 32.97
Ohio 29.7 31.49 34.09
Pennsylvania. 18.57 27.34 33.37
Vermont 25.36 37.57 36.46
Wisconsin 24.68 34.43 33.71
Mean 22.08 30.17 34.38
If a comparison is made between these reported yields and
those which are given above as possible with the recorded rain-
falls, when a favorable distribution in time occurs, it will be seen
that the mean reported yields are only about half as large as the
computed ones, and as observed ones are in localities where the
distribution of rain in time and in quantity has been favorable.
These small average yields, reported from so many states,
and agreeing so closely one with another, must be looked upon
as expressing conditions unfavorable to large yields, and condi-
tions which the best of management cannot hope wholly to
counteract.
The facts are that we are here confronted with results which
are due, in a very large measure, to the long intervals between
effective rains, to which reference has already been made. This
uneven distribution Is so general in its character that when
the yields over wide areas are brought together for comparison,
the small yields due to faulty distribution of rain so far outweigh
the large yields, where the amount of moisture ha*s been just
right, that small averages are inevitable. Nor is this condition
of things strange ; for, since the rainfall is in no way controlled
by any factor operating to cause precipitation, either when it is
Tillage to Conserve Moisture 127
wanted or in the amount which the particular crop on the par-
ticular soil may at that time need, it cannot be expected that
such a regime of chance would on the average develop the con-
ditions most favorable to large crops.
THE METHODS OP TILLAGE TO CONSERVE MOISTURE
ARE OFTEN INAPPLICABLE
If it is urged that better tillage and more systematic rota-
tions of crops, coupled with a more rational practice of fertiliza-
tion of the soil, would go a long way toward making larger
average yields, every one must admit the truth of the assertion.
But, while this is true, it must still be recognized that there are
some cases in which the methods of tillage to conserve soil mois-
ture are either wholly inapplicable or they may be applied only
with so great difficulty or with so small an effect, that they have
never come into general use for the specific purpose of saving
soil moisture.
The most important illustration in point is that of the hay
crop, with which should also be associated that of pasture as
well, when these are made from the grasses and from clover.
With these two crops, hay and pasture, which together cover a
wider acreage than any other single crop grown, there has not
been and cannot well be any method of tillage aiming specifically
to conserve soil moisture for the use of the crop.
In the thirteen states referred to when discussing the yields
of barley, oats and maize, there were cut 24,439,485 acres of
grass, making 28,314,650 tons of hay, or at the mean rate of
1.158 tons per acre, in 1879. Nearly all of this hay is made
during the months of May and June, when there is a mean rain-
fall for the thirteen states amounting to 7.83 inches, of which
not less than 2 inches is lost by percolation, and nearly .69 of an
inch is ineffective on account of showers giving less than .2 of
an inch, thus leaving an effective rain of 5.14 inches
It has been shown that clover uses 5.089 acre-inches of water
in producing one ton of dry matter, and at this rate 5.14 inches
128 Irrigation and Drainage
of effective rain ought to give a yield of 1.01 tons of dry matter,
equal to 1.188 tons of hay containing 15 per cent of water, while
the obsei'ved mean yield is 1.158 tons. Now, this yield of 1.1
tons per acre is not what a farmer calls a good yield, for 1.5
tons to 2 tons per acre of hay are often cut ; but these larger
yields are invariably associated with seasons of early heavy rain-
fall. It must be evident, then, that in the thirteen states from
Maine to eastern Kansas there are large areas where, if water
could be applied to the first crop of hay, the yield might easily
be increased 40 to 90 per cent, and there can be no question
that the aggregate extent of such areas exceeds what could be
supplied by all the water of all the rivers and all the ground
water of those states.
Then, again, in the ease of such crops as wheat, oats, barley,
rye, buckwheat, and the millets, which are sown broadcast or in
close drills, it has not been usual to practice methods of tillage
aiming specifically to save moisture ; but when the acreage of
these crops in the United States, together with that of hay and
pasture, is set aside, there remains relatively but a small part
of the cultivated lands upon which intertillage is or can well be
practiced.
These statements are made neither to depreciate the impor-
tance of conserving soil moisture by tillage nor to emphasize the
importance of irrigation, but rather that each may be seen in its
true perspective ; for the fact is, neither method is universally
adapted to meet the needs of insufficient rain at all times and in
all places. But there are conditions for which each is better
suited than the other, and for a man to know these is to make
him a better farmer.
TILLAGE TO CONSERVE SOIL MOISTURE IS CHIEFLY
EFFECTIVE IX SAVIXG THE WINTER AND
EARLY SPRING RAINS
It is not sufficiently appreciated that early and frequent till-
age where irrigation is not practiced is far more important and
effective in conserving soil moisture than later tillage can be
after the ground once becomes dry. From this it follows that
Tillage to Conserve Moisture 129
intertillage and surface tillage generally can be counted upon as
capable of saving to the crop which is to be grown upon the
ground only a part of the rains which fall in winter and spring.
The rains of later June and July, August and September are
usually beyond the power of tillage to conserve in any marked
degree, without at the same time seriously injuring the roots of
vegetation growing upon the ground.
In the first place, after the last of June, in climates like
that of the thirteen states selected, the water of nearly all rains
is absorbed and retained in the surface 3 inches of soil or less.
It is only the rains exceeding 1 inch which penetrate more deeply
than this ; and to stir a wet soil is .to hasten the rate of evapora-
tion of moisture from the soil stirred. If, then, the roots of a
crop have dried the surface 8 inches of soil so that it contains
but 20 to 30 per cent of its full amount, and a rain falls which
wets in but 2 inches, stirring that soil can save but little of the
moisture. Further than this, when the surface of the soil has
become so dry, capillarity acts very slowly to conduct the water
downward into the soil.
In the second place, most cultivated crops, in order to take
advantage of the general fact that summer rains do not as a rule
penetrate deeply into the soil, develop a system of roots ex-
tremely close to the surface of the ground, where momentary ad-
vantage may be taken of those rains which do not wet in deeply ;
and hence it is that in sub-humid climates, and after a dry time
in all climates, surface cultivation right after a rain may do posi-
tive injury by cutting off roots which have been developed to
take advantage of such rains, while at the same time the rate
of evaporation from the stirred soil has been increased. Hex*e,
again, it is seen that rigid physical laws and conditions have set
limitations to the methods of tillage as a substitute for irrigation.
MIDSUMMER AND EARLY FALL CROPS DIFFICULT TO
GROW WITHOUT IRRIGATION
The fact that after early summer the surface of the ground
usually becomes quite dry, coupled with the other fact that water
130 Irrigation mid Drainage
percolates and travels downward through such soil with difficulty,
makes the growing of a second crop of almost any kind very
difficult and uncertain by methods of tillage unaided by irriga-
tion. Every one is familiar with the fact of short pastures in
midsummer and early fall, and that seeoud crops of hay can be
raised only in exceptional seasons, and even then they are seldom
heavy.
The difficulty in these cases is not that less rain falls during
the summer and autumn, for the measured amount is actually
greater. Neither is it true that they will not grow because it is
out of season, for when plenty of water is supplied heavy crops
of grass are obtained for the second cutting. As a matter of
fact, the summer rains are less effective because they are re-
tained so near to the surface as not to come within reach of the
roots before they are lost by surface evaporation.
In our own experiments in irrigating clover, there has been
secured for the second crop of clover hay 1.789 tons in 1895,
2.035 tons in 1896, and 1.648 tons of hay, containing 15 per cent
of water, in 1897, or an average for three years of 1.824 tons per
acre. When it is recalled that the average yield of hay per acre
for the thirteen states cited is but little more than 1 ton per acre
for the first crop, when the rains have their maximum effective-
ness, it is plain that without irrigation it is not possible to grow
a paying second crop of hay to any extent in either the sub-
humid or humid parts of the United States. Further than this,
on account of the small effectiveness of summer rains, it is often
quite impossible to secure a catch of clover with any of the small
grains, while with irrigation the catch would be positively as-
sured every year. These are cases in which present methods of
tillage can do nothing, but in which irrigation will give certain
results.
The present season we put into the silo 6,552 pounds of
clover and volunteer barley, cut from .58 acres of ground upon
which had been harvested 45 bushels of barley to the acre. This
was rendered possible by irrigating the land, and thus forcing
the new seeding of clover after the crop was removed. In this
way it was possible to get two good crops in one season from the
Fall Ploiving to Conserve Moisture 131
same piece of ground ; namely, 45 bushels of barley per acre,
and the equivalent of 1.4 tons of hay containing 15 per cent of
water. Only very extraordinary seasons would by any method
of tillage permit this to be done.
MEANS OP CONSERVING MOISTURE
1. Fall Ploiving to Conserve Moisture
In those parts of the world where winter precipita-
tion is not large, so as to over-saturate the soil, and
so as to cause the running together of soils, and thus
destroy their tilth, fall plowing may be found very
desirable when its chief object is to diminish surface
evaporation during the winter and early spring, and
where it is desirable to facilitate the ready and deeper
penetration of the water into the soil which, during
the growing season, has become dried to considerable
depths.
In order that fall plowing may be most effective in
this way, it should be done as late as practicable, so
that its looseness may not be destroyed by the early
rains, and its usefulness as a mulch thus reduced; and
also in order that it may allow the later rains and melt-
ing snows to drop easily and more completely through
it, when surface drainage will be prevented, and loss
by evaporation will be reduced to the minimum. In
such conditions capillarity and gravity may together
aid in conveying the water into the second, third and
fourth feet, where it will become most effective in
supplementing the spring and earh^ summer rains.
The writer has shown, in "The Soil," p. 187, that
132 Irrigation and Drainage
land in Wisconsin fall -plowed late in the season was
found in the spring, even as late as Maj^ 14, to eon-
tain not less than 6 pounds of water to the square
foot more than similar adjacent land not so treated.
This is equivalent to 1.15 inches of rain, a very
important quantity to have been stored in the soil at
so late a period and iu such a position that inter-
tillage is certain to retain it for service when it is
needed.
It will be readily appreciated that this sort of tillage
to conserve moisture is most important in the sub-
humid and humid climates, whenever those dry seasons
occur which close the year with an under -supply of
soil moisture.
It should not be inferred that this sort of tillage to
save moisture must be confined to such lands as are to
be sowed to small grains in the spring, or even planted
to corn or potatoes. It is particularly desirable in all
lines of orcharding, and where small fruits and grapes
are grown. The laying down and covering of the
plants need not prevent it, for the plowing may imme-
diately precede the laying down. In the growing of
small fruits without irrigation, the late fall tillage, just
before the ground freezes, is a matter of considerable
moment, because with strawberries, raspberries and
blackberries it very often happens that a shortage of
soil moisture just at the fruiting season results in a
very serious loss through a reduction of the yield,
and late, deep tillage will usually lessen this danger.
If it should be urged by some that this practice
applied to orchards would tend to stimulate a too late
Suhsoiling to Conserve Moisture
133
growth of wood in the fall, and thus lead to danger
from winter -killing, the reply is that when it is done
late, just before freezing up, there can be no danger
on this score.
2. Suhsoiling to Conserve Moisture
Subsoiling to conserve soil moisture cannot have
the extended practice that methods of surface tillage
should, but there are cases when it is quite likely to
prove sufficiently helpful to pay for the relatively heavy
expense which it involves. In view of this fact, and
because it is being urged particularly in the sub-humid
1'-"F00T
^tNOi
a"-"
A''- '
GAIN.Ei)-:l4.LB5----;
:Lq-5rTi25LB5:-:
5™"
• 1^1^^- f ^ t^^f^t^^v^:^'"tf fe|? 'f^^^f • '4^-fv';
Fig. 24. Method of determining the influence of subsoiling.
belt, the principles underlying the practice should be
clearly understood.
The method used to demonstrate the influence of
subsoiling in retaining the rains which fall upon the
134 Irrigation and Drainage
ground is illustrated in Fig. 24, where all losses by
surface evaporation were prevented by placing an air-
tight cover over the areas under experiment. In order
that the extreme influence of subsoiling might be
ascertained, 8 inches of the surface soil was completely
removed from an area 6x6 feet on a side, and when
the subsoil had been spaded to a depth of 13 inches
more it was returned to its place without firming in any
way, except to smooth the surface with a plank pressed
down by the weight of a man. After samples of soil
had been taken from this and the adjacent area, to give
the existing water content, water was slowly sprinkled
over the two surfaces until 254.41 pounds, or 1.36
inches, had been added to each, and then they were
covered, as shown in the figure, and allowed to stand
from June 11 until June 15, when the covers were
removed and samples of soil again taken, to demon-
strate what changes had occurred.
When this was done it was found that the water
added had effected the changes which are recorded in
the table which follows :
Subsoiled
Not snbsoiled
Difference
LBS.
LBS.
LBS.
The first foot gained
124.6
102.1
+22.5
The second foot gained . . .
12.f>l
10.34
+62.23
The third foot gained
38.22
12.05
+26.17
The fourth foot gained . - .
33.26
3.82
+29.43
The fifth foot lo«;t
2.29
19.5
—17.21
X lie ilJ-Ltl l.\J\J\j l.\JO\J ' -••••••
Total water gained
268.65
128.31
Total water added
254.41
254.41
Difference
. +14.24
—126.1
Suhsoiling to Conserve MoisUire 135
It will thus be seen that the subsoiled ground,
under conditions where no evaporation could take place
from the surface, had not only retained all the water
which had been added to it, but that it had actually
gained by capillarity from the adjacent soil 14.24
pounds additional. The ground not subsoiled, on the
other hand, had actually lost, without evaporation from
the surface of the soil, 126.1 pounds of water.
In a second experiment, which was handled in the
same way, except that no water was added to the sur-
face, the treated soil was allowed to stand from June
26 to July 2, covered so that no evaporation could
take place from the surface, the object being to learn
whether capillary action would draw moisture from
below into the subsoiled earth, and thus increase its
water supply. The changes which took place are
shown by the following figures :
On Subsoiled Ground
1st foot 2nd foot 3rd foot 4th foot 5th foot
PER CENT PER CENT PER CENT PER CENT PER CENT
June 26{^f^\*^/®} 23.29 21.89 17.85 14.14 19.55
J"^y " {^t°cloTe^} 22.66 22.50 17.49 14.45 20.27
Change — .63 + .61 — .36 + .31 + .72
On Ground not Subsoiled
June 26— start... 22.52 20.67 17.74 15.06 19.34
July 2— close 23.97 22.09 18.92 14.62 18.38
Change +1.45 +1.32 +1.18 —.44 —.96
It appears from these results that there was but
136 Irrigation mid Drainage
little tendency for the deeper soil water to pass upward
by capillarity into the subsoiled earth. But quite the
opposite was the case with the ground not subsoiled,
for here the upper 3 feet had each gained more than
1 per cent of their dry weight of water. Express-
ing the movement which had taken place during the
6 days in pounds of water on the 36 square feet of
surface, we find that the surface 3 feet had gained
129.69 pounds, while the lower 2 feet had lost 53.52
pounds, leaving an absolute gain of 76.17 pounds. In
the case of the subsoiled ground, the surface 3 feet
showed a loss of 11.14 pounds, and the lower 2 feet a
-gain of 39.38, making an absolute gain to the area of
only 28.24 pounds.
In another field trial, when a piece of land was
subsoiled on October 22, while a strip on each side of
this was plowed without subsoiliug, the water in the
soil was found in the spring to be distributed in the
manner indicated below :
First foot
Second foot
Third foot
Fourth foot
Total 69.10 68.76 +. 34
Here it will be seen that the surface foot of
subsoiled ground contained nearlj^ 2 pounds less
water than that not subsoiled, but that the absolute
Subsoiled
in the field
Not subsoiled
in the field
Difference
LBS.
LBS.
LBS.
15.47
17.41
—1.94
17.61
16.81
+1.30
18.19
17.84
+ .35
17.83
17.20
+ .63
SuhsoiUng to Conserve Moisture 137
amount of water in the two cases is practically the
same.
In a fourth experiment to show the effect of sub-
soiling in the spring on the water content of the soil
in the fall, one of the small areas already described was
allowed to stand exposed from June until September,
75 days, without in any way disturbing the surface,
except to keep it free from weeds by shaving them off
with a sharp hoe. The results were these :
First foot ■ . .
Second foot
Third foot . .
Fourth foot .
Fifth foot . .
Here, again, the results have the same general char-
acter as they did when the subsoil period was from
October to April, the surface foot of subsoiled ground
being the dryest, while the next 3 feet are more moist.
When the effect of subsoiling in this case is expressed
in inches of rain, the gain in the saving of soil moisture
amounts to 1.64 inches, which is a very important
amount.
The effects of subsoiling probably do not last much
longer than a single season, unless there has been but
little rain, so that the ground has never been thoroughly
saturated, permitting it to again settle together. In
the case of the field trial here reported, samples of soil
were taken on the same ground April 8, April 16, and
Subsoilod
ground
Not subsoiled
ground
Difference
PER CENT
PER CENT
PER CENT
17.07
18.91
—1.84
23.29
19.42
+3.87
22.76
17.78
+4.98
16.35
14.19
+2.16
18.14
19.20
—1.06
138 Irrigation and Drainage
again Maj' 5, in order to discover whether in that time
progressive changes would take place. Between the
first and last date there had been a total rainfall of 5.33
inches, making conditions very favorable indeed to
obliterate the effects of the subsoiling in a short time.
The changes which these rains, together with the fitting
and planting of the ground, produced, are shown in the
table below:
. April 8 '-- April 16
Not Kot
Subsoiled subsoiled Difference SubsoUed subsoUed Difference
PER CEXT PEE CENT PER CENT PER CEXT PER CENT PER CENT
First ft 19.58 22.04 —2.46 20.80 22.88 —2.08
Second ft.. 19.01 17.61 +1-40 18.62 18.97 — .35
Third ft... 17.39 17.06 +.33 16.48 16.70 —.22
Fourth ft.. 16.79 16.20 +.59 16.11 16.50 —.39
' May 5 ■
Not
Subsoiled subsoiled Difference
PER CENT PER CENT PER CENT
Firstfoot 21.28 21.34 —.06
Second foot 19.02 19.11 —.09
Third foot 19.11 18.37 +.74
Fourth foot 16.67 17 —.33
It will be seen that the difference between the water
in the soil under the two treatments becomes less each
time the samples are taken, and that on May 5 the dif-
ference between them had nearly disappeared. But it
should be observed that this close agreement at the last
time may be more apparent than real, on account of the
fact that a rain of 1.3 inches had fallen on May 1, and
it is possible that time enough had not yet elapsed to
allow an equilibrium to be established.
Effects of Suhsoiling 139
EXPLANATION OP THE MOISTURE EB'FECTS OF
SUBSOILING
The results stated show that suhsoiling produces several very
distinct effects, so far as soil moisture is concerned, and these
may be stated as follows :
1. Subsoiling increases the percentage capacity for water of
the soil stirred.
2. Subsoiling decreases the capillary conducting power of the
soil stirred.
3. Subsoiling increases the rate of percolation through the
soil stirred, or its gravitational conducting capacity.
In order to understand how these effects are produced by sub-
soiling, if is necessary to have clearly in mind the nature of the
physical changes in the soil which the operation in question sets
up. In the small plot experiments which have been cited, the
subsoiling had the effect of increasing the pore space in the soil
stirred at the rate of over 245 cubic inches per cubic foot, or 14.2
per cent. Further than this, the pore space so added consisted in
a large measure of cavities which were so large that air and water
would move through them in obedience to the laws which govern
the flow of water through large pipes, rather than those control-
ling the flow through capillary tubes.
It must here be born in mind that the increase of space was
made as large as it could well be, and hence that the results have
a maximum value.
Hoio suhsoiling increases the loater capacity of the soil stirred. —
When a soil is broken into lumps which lie loosely together, and
these lumps are saturated with water, the many lumps behave
toward that water much as if each were a short column of soil
which is in contact with standing water. The surface film of
water which spans the pores at the surface of the saturated lump
of soil has a definite strength, and, if the lump is not too large,
can hold every cavity within that lump completely full of water,
just as the lump of sugar dipped into the tea and then withdrawn
comes forth completely filled with the fluid. But when the soil
140 Irrigation and Drainage
is compact, so that each portion is part of one long and continuous
mass extending downward several feet before water is reached,
the surface tension of the water is not strong enough to maintain
the soil cavities full of water, and a part drains away downward.
It is easy to demonstrate the nature of this action with a bit of
candle wicking 2 or 3 feet long, or with two or three folds of cot-
ton wrapping twine loosely twisted together. Placing this in a
basin of water and letting it become saturated, if it is then raised
out by both ends, holding it nearly horizontal and straight, the
water very soon ceases to drip from it ; but if it is allowed to sag
in the middle, the water will begin to drip rapidly, and will con-
tinue to do so until a new equilibrium has been reached. The
string will lose its water still more rapidly and completely if it is
simply suspended from one end, when it then represents the long-
est column of soil.
How subsailing decreases the cajyillary conducting power of
soils. — When large open spaces have been developed in a soil by
any means, then every such cavity cuts off a part of the capil-
lary passageways through which the water might travel by capillary
conduction, thus making the amount of water which may move in
a given direction proportionally smaller. This being true, when
rain falls upon subsoiled ground it travels downward very slowly
through it until after the soil has become completely filled, and
drainage or pei"Colation takes place. If, then, the shower is not
heavy enough to completely fill this subsoiled layer, it is nearly
all retained within it ; whereas, when the capillary connection is
good, then so soon as the surface layer becomes wetter than that
below, the water begins to move under the impulse of capillarity,
and will continue to do so until a balance has been reached.
On the other hand, when the surface of the subsoiled ground
has become dryer through evaporation or by root action, water
from below will not enter it as rapidly as it will soil not so treated.
It is thus capable of acting as a deep mulch, to diminish the loss
of water by capillary movement upward. But should conditions
chance to be such that the whole root system of the crop has been
developed within this subsoiled layer, then a rapidly-growing crop
upon it might suffer for want of water when there was an abun-
Effects of Subsoiling 141
dance of it in the unstirred soil below, but now prevented from
rising into the root zone by the reduced rate at which it is possible
for the water to rise.
This is a matter of great importance to comprehend, because
in a humid climate, where the subsoils frequently become satu-
rated with water, rendering them unfit for the feeding ground of
roots, to develop a deep mulch over this by subsoiling would tend
to maintain this lower soil permanently in a condition which
excludes the roots of plants from it, while at the same time that
water cannot rise into the loosened soil above, and a drought
actually occurs when, if the field had not been subsoiled, a good
supply of water might easily be reached by the crop.
In the arid and sub-humid regions, the saturated subsoil is
rarely found, except for short periods, at long intervals apart,
and hence there is little danger from this score in subsoiling in
these climates.
How subsoiling allows the water to enter the soil more readily. —
From what has already been said, it will be understood that it is
only after the subsoiled layer has become saturated that water
begins- to percolate through it, and so to store itself in the
undisturbed layer below. But when rain enough has fallen to
accomplish this result, then whatever else falls drops readily and
rapidly through it, not only because there are wider channels for
the water to move through under the stress of gravity, but because
from an open soil the air escapes quickly and readily, thus making
place for the water which cannot enter until the space for it has
been vacated. The water entering the soil in time of rain or irri-
gation is like water entering an open-mouthed jug, which can only
do so as rapidly as the air is permitted to escape.
A larger percentage of the icater contained by subsoiled ground
available to crops. — With all soils, of whatever kind, there is a cer-
tain amount of water they contain which it is impossible for the
roots of plants to remove with sufficient rapidity to meet their
needs, and this amount is relatively smaller in the coarse-grained
soils than it is in those having a finer texture. But whenever any
soil has been subsoiled, and its water-holding power thereby
increased, this extra amount of water becomes wholly available to
142 Irrigation and Drainage
the plant ; and if this amount would have been lost, either by
downward percolation or by evaporation from the surface, then the
subsoiling has been a gain.
3. Earth Mulches
When the damp surface of a soil is covered with a
dry layer of earth, the rate of evaporation from it is
very much decreased. It is because of this fact that
thorough surface tillage is able to so conserve the soil
moisture stored in the upper four to sis feet of culti-
vated fields that fair crops may be grown with very
little rain ; and it is in the effective handling of these
mulches that the hope of farmers in sub -humid districts
must be laid.
Conditions modifying the effectiveness of mulches. — The laws
which govern the loss of water through mulches have not yet
been sufficiently worked out to permit a full discussion of this
important subject, but several important facts have been defi-
nitely settled, and may be here stated.
In the first place, when other conditions are the same, the
thicker or deeper the layer of loose, dry soil is, the less rapidly
can the soil moisture pass upward through it, to be lost by
evaporation.
It was found, for example, that when soil covered with no
mulch lost water in the still air of the laboratory at the rate of
4.375 acre-inches per 100 days, the same soil stirred to a depth
of .5 inches lost but 4.017 acre-inches, and when stirred to a
depth of .75 inches lost 3.169 acre -inches in the same time. In
another ease, when the loss of water from the unmulehed surface
was 6.2 acre-inches per 100 days, stirring this same soil to a
depth of 1 inch reduced the loss to 4 acre -inches, while stirring
it to a depth of 2 inches left the loss but 2.8 acre -inches per
100 days.
So, too, when corn was cultivated to a depth of 1 to 1.5
Mulches to Conserve Moisture 143
inches with a Tower cultivator, and adjacent rows were culti-
vated to a depth of 3 inches with narrow shovels, it was found at
the end of the season that the ground cultivated 3 inches deep
contained 1.478 inches more water than the 1-inch cultivation
did in the upper 4 feet, the conditions of the soil being as repre-
sented below :
1st foot 2nd foot 3rd foot 4th foot
PEK CENT PER CENT PEE CENT PER CENT
Cultivated 3 inches deep 23.14 23.3 21.94 22.46
Cultivated 1 inch deep 22.7 21.08 19.65 19.58
Difference .44 2.22 2.29 2.88
These differences do not show the amount of water which the
deeper mulch saved, because at several times during the season
the rains may have brought the soil of the two kinds of treat-
ment very close together in their water content, the results above
being simply the final difference. They do show, however, how
much more moist one soil was kept than the other, and, hence,
how much better were the conditions in one case than in the
other for plant growth.
That the full significance of such differences in soil moisture
in crop production may be better appreciated, Fig. 25 shows the
growth of corn under every way similar conditions, except that
the amounts of water in the soil in which the corn was large
and in which it was small were as stated in the table which
follows :
Moisture in soil Moisture in soil
of largest corn of smallest corn
PER CENT . PER CENT Difference
First foot 13.29 10.18 3.11
Second foot 17.23 16.33 .9
Third foot 19.17 18.63 1.08
Fourth foot 16.21 15.48 .73
These differences, it will be noted, are much smaller than in
the case cited above. But let it be observed that the difference in
the surface foot here is very much larger than there, and it is the
shortage of water in this layer which is chiefly responsible for the
difference in growth shown in the figure.
144
Irrigation and Drainage
The character of the mulch, also, has an important influence
on the amount of water which is permitted to escape through it.
Thus, it was found that when the same soil was covered to a depth
Fig. 25.
Difference in grcvvth of corn where there is a difference of
3 per cent of soil moisture in the surface foot.
of 2 inches with mulches of different kinds, the observed loss of
water per 100 days was as stated below :
INCHES
Through 2-inch mulch of coarse sand l.l
" " " " black marsh soils 3.9
" " " ' fine clay loam 3.9
" " " " dry peat 2
" " " " clay loam, crumb-form 2.8
From these results it is seen that a coarse-grained texture
produces a better mulch than one extremely fine ; that is, the loss
of water by evaporation through the coarsest sand was less rapid
than it was through the fine sand, and it was more rapid through
the finely powdered clay loam than it was througli the same soil
left in the crumbled condition in which we usually find it when
the soil is in good tilth. The small loss from the peat mulch, too,
was due largely to the fact that it did not rub down to a iine
texture.
Just why this law holds for soil mulches cannot now be stated,
except that it seems evident that the water is not lost by direct
evaporation at the surface of the damp soil, for in that case we
should expect the largest losses to take place from the mulches
having the most open structure, and the least when the diameter
Middles to Conserve Moisture 145
of the pore spaces is smallest, but which observation proves not
to be true. The only explanation which now occurs to the writer
I'or the law is, that even in the air-dry condition of soil, the film
of moisture still investing the soil grains, although so extremely
thin, is subject to the same disturbance by evaporation at the
exposed surface that it is when that film is much thicker, as in the
case of soils containing the right amount of moisture for plant
growth, and when evaporation from the surface takes place
rapidly.
Earth mulches lose in effectiveness with age. — When a good
earth mulch has been developed, it does not remain equally effec-
tive for an indefinite period, even if no rain falls upon it. This is
particularly true early in the season, when the amount of soil
moisture is high, and when it tends to creep into the lower part
of the mulch, saturating it and causing the open texture to
disappear by breaking down the crumb structure, and thus restor-
ing the original and normal capillary power. A soil mulch devel-
oped to a depth of two or three inches thus grows gradually
thinner with age by reverting to the original condition. This be-
ing true, it is necessary, when the greatest protection is desired,
to repeat the stirring of the soil as often as observation shows that
its effectiveness has been impaired.
Mulches that are not made from soil. — By far the largest part
of the protection offered against the loss of water by sui'face
evaporation from the soil is and must be furnished by mulches
developed from the soil itself. But it should be understood that
all vegetation growing upon the surface of a field, whether it
completely covers the ground or not, exerts a protective influence,
tending to diminish the loss of water from the surface of the
ground. This protection comes partly from shading the ground,
partly from a reduction of the wind velocity close to the surface,
and partly from the tendency of vegetation, by the transpiration
from its foliage, to saturate the air with moisture, and so reduce
the rate of evaporation which otherwise would be possible.
Even in pastures where the grass is short, if it is only close
and completely covers the ground with its foliage, the mulching
influence is marked. Hence, in order to get the largest returns
146 Irrigation and Drainage
from the natural rainfall on pasture land, great care should be
taken to keep it in such condition that the whole surface is well
and closely covered with vegetation. Of course, the same remarks
apply to meadow lands.
Too close pasturing is very wasteful in every way. The
animals themselves are not fed properly, the grass is not permitted
to have foliage enough for the most vigorous growth, and so much
of the surface of the ground is exposed to the sun that evapora-
tion directly from the soil is rapid and a dead loss, not only doing
no good in itself, but throwing out of use the upper layer of soil,
in which the nitrifying processes should be permitted to go for-
ward rapidly, because it is too dry for them.
The surface dressing of meadows with a good coating of
farmyard manure, and then harrowing this thoroughly to spread it
evenly over the surface, is extremely beneficial, not simply because
of the plant-food which it contains, but because of the mulching
effect which it furnishes to shade the naked spots of soil and
those which are only thinly covered. When this dressing is
applied very early, and is early spread over the surface, while
the soil is yet damp, it, of course, does the most good, both as a
mulch and as a plant -food ; for then fermentation goes on better
in the manure, and the moisture dissolves out the soluble parts
and conveys it to the roots of the grass. Then, too, in the ease
of thin meadows, if new grass and clover seed are added at the
same time, before the harrowing, much of it will be sufficiently
covered by the harrowing and shaded by the manure to allow it to
germinate, and thus thicken up the meadow and bring it back to
its proper condition.
Harrowing and rolling small grain after it is up. — When the
ground is closely covered with plants, as in the case of oats,
wheat and barley sowed broadcast or in close drills, advantage
has sometimes been found in either harrowing the ground or in
rolling it for the express purpose of changing the character of the
surface. The changes thus wrought have sometimes a double
effectiveness, in that a thin mulch is produced which in a meas-
ure reduces the direct loss of water through the surface soil by
evaporation from it ; and in breaking up a crust which forms
Earhj Tillage to Conserve Moisture 147
over plowed fields when a considerable evaporation has taken
place from the wet surface, and which, on account of the shrink-
age and of the salts brought to the surface by the soil water, tend
to close up the soil pores, and thus interfere with the. proper
entrance of air to it, which is essential to the best results. Roll-
ing in such cases will seldom do much good, except where the
ground was left somewhat uneven at the time of seeding, either
by the drill ridges or by those left by the harrow, or unless there
are many small lumps, which the rolling tends to break down,
forming from them and the ridges, or both, a thin mulch. The
harrowing in such cases has a wider range than rolling, and is
often likely to be more effective. But neither of these treat-
ments should be given except when the soil of the field is dry
and crumbly at the surface, for otherwise no mulch will be formed,
and the effect would be to increase rather than diminish the loss
of water from the soil by surface evaporation from it.
4. Early Tillage to Conserve Moisture
It has already been pointed out that tillage to
conserve moisture is most useful in humid climates
when it is applied as early in the season as the condi-
tion of the soil will admit. But the case is stated in
the most general terms when it is said that tillage,
to save moisture, should be given to the soil just as
soon after the wetting of the surface as it is possi-
ble to do so without puddling or otherwise injuring
its texture.
Let it be fully understood that tillage to save soil
moisture is concerned almost wholly with the saving
of that which has penetrated the soil to a depth exceed-
ing that of the mulch developed by stirring, As a
thoroughly effective soil mulch cannot be readily made
having a depth less than 2 to 3 inches, it follows that
148 Irrigation and Drainage
tillage to conserve soil moisture is chiefly concerned
with saving moisture which has penetrated the ground
to a depth exceeding 2.5 to 3 or more inches. The
moisture which is caught and held by the soil closer
to the surface than stated must usually be taken up
directly by the surface feeding roots, or it must be
lost by surface evaporation.
When the snows and frosts of winter have melted,
and the earliest spring i-ains have come, the soil is
usually left so moist as to be fully saturated with
water to a depth exceeding 1, 2, and even 3 feet,
according as the snows or rains have been copious or
light. At the same time, the texture of the surface
soil has been so changed as to place it in the very
best possible condition for rapidly conveying the deeper
soil -water to the surface, where, if the sun shiues and
a brisk, dry wind is blowing, it will be lost with great
rapiditj^ sometimes in single exceptionally favorable
days amounting to 2, 3, and even 4 pounds per square
foot per day, equivalent to more than 40, 60 and 80
tons per acre.
But these high rates of loss are not m'aintained,
fortunatelj% for long periods of time, even when there
has been no effort made to prevent them. We have,
however, measured losses during seven days amounting
to 9.13 pounds per square foot, T)r at a daily rate of
1.3 pounds; and in four days a rate as high as 1.77
pounds per square foot. Under extremely favorable
conditions, and where the surface of the soil was kept
continuously wet, we have measured a mean daily loss
by evaporation as great as 2.37 pounds for fine sand,
Early Tillage to Conserve Moisture 149
and 2.05 pounds for a elaj- loam, per day and per
square foot.
As soon as the surface of the soil becomes air -dry,
the rate of evaporation from it is very much slower,
for in this condition it does not conduct the water
upward as rapidly as when nearly saturated. Early
tUlage contributes to this end, and thus greatly di-
minishes the losses which would occur early in the
season.
There is no tool made which produces a more
effective mulch than the common plow, which cuts off
completely a layer of soil of the depth desired and
lays it down bottom up in a loose, crumbled condition,
reducing the capillary conducting power to the mini-
mum. It is not possible, however, to use the plow as
early in the season as some of the other tools, like the
harrow ; neither is it possible to cover the ground as
rapidly with it. Further than this, it is often unde-
sirable to stir the soil as deep as it must be worked
with the plow, in order to make a good mulch ; and
so one or another form of harrow is used instead.
When small grains are sowed on fall plowing, or
on corn or potato ground without plowing, it is
important to start the surface -working tools at the
very earliest possible moment, not simply to save
moisture by developing a mulch, but to aerate and
warm up the surface soil, so that the nitrates may
begin to be developed and placed in readiness for the
crop which is to follow. It is this saving of moisture,
and the early and abundant development of soluble
plant -food, which is invariably associated with and the
150 Irrigation and Drainage
direct result of a thorough preparation of the seed-
bed, which has always led the most successful farmers
to insist upon the importance of a good seed-bed.
Let it be remembered that it is the early stirring
of the soil, rather than the early planting of the seed,
which is the all -important point to be insisted upon.
Nothing is gained bj^ putting seed in a soil which is
too cold ; but several days may often be saved in bring-
ing the soil to the right temperature by stirring a suf-
ficient depth of it for the seed-bed, and getting rid
of the surplus water which it contains by cutting it
loose from the wet soil below, and at the same time
concentrating the heat from the sun in this stirred
hiyer, because loosening it has made it a poor con-
ductor to the unstirred cold soil below it.
Even when ground is not to be planted until quite
late, as in the case of corn and potatoes, it is a far
Ijetter practice to plow as early as other labor will per-
mit, than to leave it unsth-red until near the planting
time, because the early fitting develops plant -food and
gets it in readiness for the crop ; because it saves
moisture ; because it prevents clods from forming, and
insures a more perfect tilth, and because it allows one
and sometimes two crops of weeds to be killed before
the planting. This last advantage is a yerj important
one, because weeds can be killed much more cheaply'
and effectively when there is nothing on the gi-ound
in the way, and because it is a very wasteful practice
to permit weeds to start in a field, to use up both the
moisture and the plant -food which will be needed by
the crop. It is much better to plant late, and take
Ploiving Under Green Manures 151
time enough to have everything in the best possible
condition, than to rush the seed in early and expect
to do the fitting and weed -killing afterward.
The importance of observing the practice here
pointed out increases more and more as we pass from
the more humid climates to the semi -humid ones.
Be it remembered that it is important not simply from
the soil- moisture side, but from the plant-food side as
well ; for plant -food cannot be developed in the soil
without the right conditions of moisture, temperature
and air, all of which are secured by early, thorough and
frequent tillage before the seed is in the ground.
5. The Danger of Plotving Under Green Manures
In both humid and sub-humid climates, where irri-
gation is not practiced, the use of green crops for ma-
nures in the spring cannot be looked upon as always
a rational practice, unless it be on grounds which are
naturally sub -irrigated, or for other reasons are natu-
rally too wet. The difficulties standing in the way of
this practice are these : If the green manure crop
should be rye, or anything of that character, its ten-
dency to remove from the soil all of the nitrates and
other soluble plant -foods as rapidly as they can be
formed leaves the soil for the time being impover-
ished ; and it can be readily understood that if another
crop like corn or potatoes is put at once upon the
ground, in weather when germination takes place
quickly, this crop would find itself placed under con-
ditions in which it will be forced to wait, or at best to
152 Irrigation and Drainage
grow slowly, until time enough shall have elapsed for
the processes of fermentation to be set up in the green
crop which shall reconvert it into available plant-
food. But if the spring should chance to be a dry
one, so that the crop of green manure has itself left
the soil deficient in moisture, or if the capacity of the
soil for moisture is naturally small, then there will be
present in the soil neither moisture enough to make
the green crop .turned under ferment rapidly, nor to
enable the planted crop to make the best growth, even
where there is an abundance of plant -food in the
soil.
The sowing of a catch crop in the fall in humid
climates is not open to the same objection, for then
this crop has a tendency to gather up available ni-
trates which develop during the warm part of the fall,
after the crop has been taken off the ground, and to
carry them through the winter in an insoluble form,
so that they are not lost by drainage. But to bring
them into requisition, especially if the season or soil
is at all dry, it is important that this should be turned
under early, and a sufficient interval of time allowed
to intervene for fermentation to take place before the
seed of the new crop is put upon the ground.
In sub -humid climates, on soils that are not sub-
ject to washing, it is very doubtful if there is any
advantage to be gained from catch crops, as such,
even when sown in the fall ; for in those cases there is
neither winter nor spring leaching of the soil, and as
there is naturally a deficiency of soil moisture, the indi-
cations are that very early fall plowing, to develop a
Summer Fallowing and Soil Moisture 153
new mulch to lessen further evaporation during the
fall and winter, and to permit nitrification in the fall to
be carried forward, is likely to leave the soil in a much
better condition for the next season, both as to moisture
and available nitrates, than could be hoped for by the
other method.
It is not only difficult to get a good catch crop in the
fall on account of deficient moisture, but there is during
the growing season of the sub -humid climate so little
moisture that a rapid rate of nitrification in the soil
is impossible, and hence all the time which can be had
for this purpose is needed in order to have enough
nitrates developed for the crop the next year.
6. Summer Fallowing in Relation to Soil Moisture
The old practice of summer fallowing, which it has
been the fashion for writers on agricultural chemistry
to discourage of late years, has really much more of
merit in it, as indeed practical experience has proved,
than has been recently taught. It is not here intended
to convey the idea that there are not soils and climates
in which, in the majority of seasons, it would be better
not to summer fallow, on account of there being danger
of an excessive development of nitrates, which would be
lost by drainage ; but there is much to suggest that in
rich soils which are usually deficient in soil moisture,
as in many sub -humid sections, there is not mois-
ture enough in a single year to develop the requisite
amount of plant -food and to mature the crop as well,
and hence, that some form of summer fallowing, or
154 Irrigation and Drainage
practice which is equivalent to it in effect, will be found
to give better results than steady cropping, either with
or without catch crops.
INFLUENCE OF SU30IER FALLOWING ON SOIL MOIS-
TURE AND ON PLANT -FOOD
In a study on the influence of summer fallowing on the water
content of the soil, it was found that the effect still showed, even
at the end of the following season, after a crop had been matured
on the ground. In order to show how great this influence may
be, the results of the study are cited here, giving first the con-
dition of the soil in the spring, when the fallowing experiment
was begun. The results cited are from three adjacent plots, the
middle plot being the one bearing the crop. The table which
follows shows the water content of the plots as given by three
determinations, on May 22, June II, and June 17, the averages
being given in every ease, and the data from the two fallow
plots being combined:
0-12 inches
12-18 "
24-30 "
3&-42 "
48-52 "
Mean 19.20 18.92
Here it will be seen that there is a slight tendency for the
ground left fallow to be a little wetter than that which was to
bear the crop, but this difference is not as large as the table
shows, because the fallowing effect had begun to show its in-
fluence somewhat when the last two sets of samples were taken,
corn having already begun to grow upon the intervening plot.
At the end of the growing season, August 24, the difference
Ground to be
left fallow
Ground not to be
left fallow
PER CENT
PER CENT
23.63
21.49
19.78
18.57
18.06
18.13
15.50
17.48
19.03
18.91
Summer Falloiving and Soil Moisture
155
in the water content of the soil under the two treatments was
found to be as given in the table below :
Not fallow ground near by
Fallow ground Not fallow ground Timothy and Clover
No crop
Corn
bluegrass
in pasture
PER CENT
PEE CENT
PER CENT
PER CENT
0-6 inches
16.23
6.97
6.55
8.39
6-12 " ....
17.74
7.8
7.62
8.48
12-18 " ....
19.88
11.6
11.49
12.42
18-24 "
19.84
11.98
13.58
13.27
24-30 " ....
18.56
10.84
13.26
13.52
40-43 " ....
15.9
4.17
18.51
d.53
In the first half of this table, where the soils are closely
similar and entirely comparable in every way, it will be seen
that the ground bearing no crop is much more moist than is
that on which the corn was grown ; and since a good degree of
moisture in the surface foot of soil is absolutely indispensable
to the processes which develop the available nitrates, it can readily
be seen how much more favorable were the conditions for the for-
mation of nitrates on the fallow ground than they were on the
ground which was not fallow. In the last two columns of the
table, there has been set down, for the sake of comparison, the
results of moisture determinations at corresponding depths on
lands bearing pastured clover in one case and hay in the other.
These samples were taken from essentially the same kinds of soil,
and but a short distance from where the other samples were
taken, and illustrate in a very forcible manner how thoroughly
the surface foot of soil in a dry time loses its moisture when it
is occupied by a crop, and how unfavorable are the conditions
for nitrification in the soil when compared with those offered by
the fallow ground.
In the following spring, after the frost was out of the ground,
and the fall and winter rains and snows had given their moisture
to the plots under experiment, samples of soil were again taken,
to learn what the relative conditions were at this time, and the
results found are given in the table below, where both the per-
156
Irrigation and Drainage
centage of water in the soil and the number of pounds of water
per cubic foot are given :
Table showing the ivater content in the spring, i/i soil which the year before had
been fallow and not fallow
Depth
Fallow
Not
fallow
Difference
Fallow
Not
fallow
Difference
of sample
PER CENT
PEK CENT
PEE CENT
LBS.
LBS.
LBS.
First foot
19.43
16.61
2.82
15.01
12.83
2.18
Second foot..,
20.55
17.76
2.79
16.4
14.17
2.23
Third foot....
18.56
16.09
2.47
17.47
15,15
2.32
Fourth foot...
17.78
15.11
2.67
17.44
14.82
2.62
Sum
66.32
56.97
9.35
This table shows that the fallow ground starts out in the
spring with 9.35 pounds of water to the square foot more than
the ground not fallow did in its upper four feet, besides having
a much higher percentage of available nitrogen in the soil. How
much greater the available nitrogen was is not known, except
that in another trial, ground which had been fallow the year
before produced practically the same yield as did a strip which
received a good 'dressing of farmyard manure.
At the end of harvest the same year, samples of soil were
again taken on the ground which had been fallow and on that
which had not been fallow, the results standing as shown below:
Table shoiving the water content of soil at the end of harvest, which the
preceding year had been fallotv, and had not been fallow
-Ground with oats-
Depth Fallow
of sample lbs.
Firstfoot 6.01
Second foot 9.05
Tliirdfoot 9.54
Fourth foot 8.93
Sum 34.13
Not
fallow
LBS.
3.74
4.45
9.30
8.43
25.92
Difference
LBS.
2.27
5.20
.24
.50
8.21
-Ground with barley-
Fallow
LBS.
9.06
11.90
12.48
14.07
47.51
Not
fallow
LBS.
7.08
10.10
10.60
11.52
39.30
Difference
LBS.
1.98
1.80
1.88
2.55
8.21
The data of this table show very clearly that summer fallow-
ing exerts a marked influence upon the relation of the soil to
Old System of Intertillage 157
water, and one which is great enough to modify the water con-
tent of the soil throughout the whole of the following season under
crop. The table shows that where oats were grown, the soil,
when the crop had been harvested, contained 8.21 pounds of
water per square foot, or 1.57 inches more than did the ground
which had not been summer fallowed the year before. The same
difference also existed on the barley ground, and in both cases
notwithstanding the fact that larger yields of both straw and
grain had been produced on the fallow ground.
7. The Old System of Intertillage
The old sj^stem of horse -hoeing, introduced by
Jethro Tail in England, and modified by Hunter, and
still later by Smith, at Lois-Weedou, has much to rec-
ommend it on fertile soils, in which there is a deficiency
of soil moisture, as is the case in the sub -humid
regions of this country. Tull was a close observer,
and early learned to appreciate the great advantage
of thorough tillage, not only in conserving soil mois-
ture, but also in developing available plant-food. He
strongly advocated planting in drills, so as to admit
of thorough and frequent stirring of the soil and with
the aid of the horse.
Hunter modified TulPs system by laying out his
fields in strips about 9 feet wide, every other one of
which was sown, while the intermediate ones were
left naked, and were frequently cultivated through the
season, and kept free from weeds. In the fall of the
year the bare strips were sown, and the others, which
had borne the crop, were plowed up and tilled in a
similar manner. His method amounted to a system
158 Irrigation and Drainage
of summei .fallowing, as that practice is now generally
understood, except that it possessed one important ad-
vantage : namely, his strips being so narrow, and hence
so numerous, that both the moisture saved by the til-
lage and the nitrates developed became available to
the plants growing along the margin. Further than
this, a part of the rain which fell upon the strips,
both by its lateral capillary movement and by the
development of roots into this unoccupied ground,
contributed to the growth of the crop as though it
had been partially irrigated, or its rainfall had been
increased, which in fact it had.
The Rev. Mr. Smith, at Lois-Weedon, in North-
amptonshire, raised wheat very successfully by still a
different modification of Tull's idea. His practice
was to sow about one peck of seed to the acre, by
dropping the grains 3 inches apart in three rows 1 foot
apart, and leaving a space 3 feet wide unplanted be-
-tween each group of three rows. These strips were
thoroughly tilled until the wheat was in bloom, and
kept free from weeds. He even went to the extent of
trenching the naked strip, bringing up some of the
subsoil and putting the surface loam into the trenches.
By his thorough tillage, thorough aeration and con-
servation of soil moisture, he was able to maintain a
yield of 18 to 20 bushels per acre without manure.
These cases of old and now generally abandoned
practice are called up here because they involve a
principle which, when correctly applied, is of great
importance in sub -humid climates, where water for
irrigation is not available. The principle referred to
Old System of Inter tillage 159
is that of using the rain which falls upon an acre of
ground to produce a crop on one -half of that same
area. For this, as a matter of fact, was the essential
thing which the Lois-Weedon system did. It is evi-
dent enough that in a country where the rain which
falls is only one -half the amount which is needed to
produce remunerative crops, if that water can be
brought to use on one -half of the area, then a fair
croiD on one -half of the ground may reasonably be
expected.
The important matter, then, is to devise a system
of planting for the various crops which shall permit
the rain which falls upon the unused area to be
brought within reach of the plants growing upon the
occupied ground. For all crops which are grown in
hills or in rows, like maize, potatoes, and various
vegetables, the problem is simple enough, as it resolves
itself into the single question of how many plants can
be matured upon the ground with the available water,
allowing for unavoidable losses. This fixes the dis-
tance between the rows and the distance between the
hills in the row. In countries where there is an
abundance of water, or where irrigation is practiced,
plants may be brought so close together that the limit-
ing factor is amount of sunshine, or available plant-
food in the soil, or air about the plant ; but in sub-
humid regions, the limiting factor is water alone, and
the distance between plants must be made such, if
necessary, that the roots of one will not encroach upon
the feeding ground of another.
The roots of the maize plant commonly spread
160 Irrigation and Drainage
laterally to a distance of 3.5 to 4.5 feet ; hence, if
necessary, the rows of corn might be placed as far as
7 to 8 feet apart, and yet be able to take moisture
from the whole field. Taking the extreme case of
rows 8 feet apart and plants 2 feet apart in the row,
the number of plants per acre would be 2,725. Sup-
posing each plant to produce a large stalk and large
ear, the total weight of dry matter for the acre might
be 2,157.5 pounds, giving 18.32 bushels of shelled
corn. This yield of dry matter per acre would call
for only 2.577 acre -inches of water to produce it, at
the rate of the results which have been obtained from
52 trials in Wisconsin.
Potato roots spread laterally to the distance of 2
to 2.5 feet ; hence these might be planted in rows 4
to 5 feet apart without having the roots overlap in
the feeding ground. The chief advantage of wider
rows for potatoes in the sub -humid climate comes in
its permitting intertillage after the vines have reached
full size, and thus better conserving the scanty mois-
ture, so important in the later development of the
tubers, and which would travel laterally by capillarity
toward the roots in case they did not reach the center.
The table which follows shows the actual distribution
of soil moisture in the upper 18 inches of a potato
field in which the rows extended east and west, and
were planted 3 feet apart, under flat cultivation ;
Old System of InferfilhKje 161
Table showing the distribution of moisture in a potato patch, June 27
Midway
between rows
Nine inches
south of row
In the row
Nine inches
north of row
Depth of sample
PER CENT
PER CEXT
PER CENT
PER CENT
6 inches
23.50
18.37
17.80
23
6-12 "
19.03
18.13
17.40
18.50
12-18 "
20.73
21.43
19.53
21.40
0-18 " 20.99 19.31 18.24 20.97
At the time these tleteriniuatious were inade, the
potato vines were about one -half full size. It will be
seen that the moisture had been withdrawn from the
soil more completely at 18 inches directly below the
center of the hill than it had at 18 inches on either
side. It does not follow from this, however, that the
i:)lants were not receiving important additions of soil
moisture from the soil in the center of the row. In
our work in irrigating potatoes, where the rows were
30 inches apart, and where ridge culture was adopted,
the water being applied in furrows about 9 inches
wide, it was found that on the boundary between the
irrigated and non- irrigated areas, the second row of
potatoes from the last water furrow had its yield
increased on the average, in 1897, 7.9 bushels per
acre, or 3,2 per cent of the yield of merchantable
tubers grown on the land not irrigated. That is to'
saj', the lateral capillary movement of the water in
irrigation influenced the yield to that extent through
a distance of about 40 inches.
In the case of corn, the second rows beyond the
last irrigating furrow showed the influence of the
water to the extent of 2.2 per cent of the non-
K
162 Irrigation and Drainage
irrigated yield, and through a distance of about 58
inches.
Then, again, in the case of some exi)erimental plots
of oats which were separated by a naked strip 2 feet
wide, and kept free from weeds by surface hoeing, the
folio wiDg distribution of water was found on July
19, 1889:
TcM* tkotcing digtribution of toil nutUture in oats and in adjacent
fallotc ttrip 2 feet wide
In oau 2 ft.
from path
In oats 1 ft.
£rc«m path
At edge
of oats
In center
of path
Difference
Depth of sample
PEBCEKT
PEK CE>T
PZBCEXT
PKH CKXT
PEE CEST
0-6 inches
8.08
11.43
3.35
6-12 "
7.51
11.80
4.29
12-18 ''
10.61
15.42
4.81
18-24 '
U.Ol
18.78
4.77
0-24 '' 10.40 10.05 10.70 14.35
It will be seen from these percentages that there is
a very marked higher per cent of water in the fallow
strip than there is immediately adjacent to it in the
oats, and from this it might be inferred that the oats
was not being fed from the fallow strip. This inference,
however, would not be correct, for it was found that
the yield of oats on a strip 1 foot wide, on the south
side of the path, was 39 i)er cent larger than from a
corresponding area in the center of the plot 12 feet
wide, while the yield on the north side of the path
was 28.7 per cent larger, showing very clearly that
there was better feeding in consequence of the narrow
2 -foot path.
In view of such facts as these, and practical experi-
Old System of Intertillage 163
ence, it is not unreasonable to expect that where there
is a deficiency of water in the soil, the small grains
may be sown in narrow strips of 4 to 6 drill rows,
9 inches apart, separated by naked strips 30 inches
wide, which may be cultivated to yield up their mois-
ture and developed nitrates to the growing grain on
either side, and thus mature heavier crops of well-
filled grain than would be possible if the seeds were
scattered evenly over ihe whole surface, none of which
could be cultivated.
Such a practice as is here suggested is manifestlj*
summer fallowing, but in a very different way, and
for quite a distinct purpose, from that usually had in
mind. Of course, it would not be urged, except on
soil and in climates in which there is an insufficient sup-
ply of soil moisture to mature the crop under ordinary
methods of handling. The method, however, has a
rational basis for sub -humid climates and for the
lighter soils of small water capacity in the more humid
climates; but it cannot be hoped that it will, under
these conditions, give as large yields per acre when
figured upon the whole area as the closer planting on
the soils better supplied with soil moisture. Neither
can it be expected that crops can be raised as cheaply
by this method as by the ordinary methods. All that
can be asserted, or can be reasonably expected, is that
better crops can be raised by it* in sub -humid climates
and on the lighter soils in humid climates, than can
be raised by the ordinary methods. It is not an easy
matter to adapt the method either to growing hay or
to maintaining pastures of the ordinary sort.
164 Irrigniion and Drainage
8. Frequetict/ of Tillage to Conserve &)il Moisture
Tillage to conserve soil moisture, like water for irrigation,
cannot be applied except at an increased cost of production.
Hence, to enltivate a field when there is nothing to be gained
from it is to be avoided. In the early part of the growing sea-
son, when the soil is so fully charged with moisture that a small
rain easily causes the soil granules to coalesce and destroy the
effectiveness of mulches, it is often desirable to repeat the culti-
vation or harrowing as often as there has been a shower of suffi-
cient intensity to establish good eapillaiy connection between
the stirred and unstirred soil.
It is often of the greatest importance that this reestablish-
ment of the mulch should take place at the earliest possible
moment, not only because of the rapid loss of water from wet
surfaces, but because of the fact that, when the surface .soil has
reached a certain degree of dryness while the deeper soil is yet
wet, the moisture of the surface layer so strengthens the upward
movement of soil moisture into that layer that not only is all
of the rain held at the surface, but a very considerable amount
of the deeper soil water is brought there also. Our studies have
proved, both by observation and by repeated experiment, that
wetting the surface of the ground may leave the deeper soil
actually dryer than it was before, and if the new mulch is not
early developed the rain may leave the surface four feet dryer
than it would have been had the rain not occurred.
Then, too, in the eai-ly part of the year, there are so many
advantages to be gained through frequent stirring of the soil,
other than the saving of moisture, that the slightest reason for
going over the ground again should lead to its being done. But
as the season advances, and the soil has become dryer to con-
siderable depths, then the desirability of frequent stiiTings of
the surface to develop or restore the texture of the mulch, is
much less. This is so, partly because when the surface of the
ground is dry, it is an excellent mulch, even though it is quite
firm and close in texture ; but also, because the smaller showers
Ridyed or Flat Cult i rat ion 165
of the later season are largely retained very close to the surface,
so that stirring the surface may hasten the evaporation of it, and
at the same time prevent a part of it from being conducted
downward into the soil by capillarity.
Farther than this, in the latter part of the season many plants
in humid climates put out new roots, which reach up extremely
close to the surface, in order to take advantage of the showers
whose waters are retained there ; and tillage at once after a
rain may do positive injury to the crop, by destroying these roots
before they have conveyed the soil moisture to the plant, heavily
laden with plant-food, as it is likely to be under these conditions.
9. Proper Depth of Surface Tillage and Ridged or
Flat Cidtivation
It will be readily inferred, from what has already been
said, that the best depth of tillage will vary with the season.
Early in the season it should almost invariably be deep, not less
than 2 to 3 inches, but rarely should it be deeper than this. The
deep stirring in the spring is to develop fertility by thoroughly
aerating the soil and making it warm, so that the nitrates are
rapidly formed. Later in the season the cultivation should be-
come more and more shallow, until, as already pointed out, it
should be finally abandoned altogether.
When it is stated that the early tillage should have a depth of
2 to 3 inches, this should be undei'stood as meaning that the
whole surface of ground not occupied b,y the plants should be
stirred to this depth, and some tool which actually displaces the
whole of the soil to a uniform depth does the best work. As a
rule, the field should not be furrowed with deep grooves and
ridges, for this method early dries out too large a volume of the
soil, and thus lessens its productive power. Indeed, it should
always be kept in mind that the surface soil in humid climates is
the most valuable soil of the field; and for this reason, after the
period of stirring for fertility is passed, as little should be moved
and allowed to become dry as will answer the needs of the mulch,
because in this condition the soil is valueless in plant feeding.
166 Irrigation and Drainage
Throwing a f eld into ridges with deep farrows between, as is
done with some of the wide-shovel cultivators, and as used to
be done generally in laying com by, has little to recommend it
except on flat fields of stiff, heavy soU, in wet climates or seasons.
The chief objection to the ridges and furrows is that they greatly
increase the evaporating surface and the amount of soil which is
thrown out of use. In the case of potatoes, however, especially
on the heavy soils, the last cultivation should be to hill them in
order to form a loose, deep, mellow soil, in which the tubers may
form and expand without meeting with excessive resistance.
Indeed, it is quite doubtful whether there are many soils in which
potatoes will not do better if hilled to some extent the last thing
before the vines spread to cover the ground. The earlier
cultivation should bv all means be flat.
10. Boiling in Relation to Soil Moisture
The roller has an extensive use in many localities
in fitting land for crops in the spring or faU. It
should be understood, however, that when the surface
of a field is finished with a heavy roller, it is left in
a condition in which its moistui"e will be rapidly lost,
and for several reasons :
1. Firming the surface reestablishes the capUlary
connection with the soil below, and the moisture is
brought to the surface quickly from depths as great
as four feet. The appearance to the eye is that -the
ground is made more moist, and so it is at the sur-
face, as a matter of fact, but it must never be for-
gotten that this is at the expense of moisture stored
deep in the ground.
2. Rolling leaves the surface smooth and even,
so that it absorbs heat rapidly from the sun on a
Rolling in Relation to Soil Moisture 167
clear day, and becomes warmer below the surface than
ground not rolled. This hastens the rate of evapo-
ration from the surface. Then, too, this smooth sur-
face allows the wind velocity to be much greater close
to the ground, and on this account the loss of water
is increased.
It is often desirable to use the heavy roller in fit-
ting ground for seed, and sometimes for the express
purpose of bringing an increased amount of moisture
to the seed, in order to hasten or to ensure germi-
nation when the soil has become dry. But when this
has been found desirable, the roller should immedi-
ately be followed with a light harrow, in order to
restore a thin mulch, which shall check the loss by
evaporation from the surface without at the same
time preventing the rise of water from below to mois-
ten the soil about the seed.
The press-drill, which has been invented to assist
germination, and avoid some of the bad effects of the
roller, is a tool employing a sound principle. The
seed is well covered to begin with, and then the soil
directly above it is firmed by the press-wheel, while
the intervening soil is left loose, to act as a mulch
and diminish the loss of water, which would be inevi-
table with the roller. This tool, however, has a much
safer application in the sub -humid regions than it
has in the East, where the soil in the spring is natu-
rally more moist, and where, for this reason, there is
danger of the seed being so closely covered that an
insufficient amount of air gets to it to enable it to
germinate properly.
168 Irrigation and Urainage
11. Lessening Destructive Effects of Winds
In sub-liumid climates, especially like those of our
western prairies, where there is a high meau wind
velocity, aud in the level districts of humid climates,
where the soils are light and sandy, with a small
water capacity, and which are lacking in adhesive
quality, the fields may suffer greatly at times, not
onh" from excessive loss of moisture, but the soil itself
maj' be greatly damaged by drifting caused by the
winds. Under such conditions, it is a matter of great
importance that the wind velocities close to the sur-
face should be reduced as much as possible.
We have, in Wisconsin, extensive areas of light
lands which almost every year suffer severely from
the drifting action of the winds. On these lands,
wherever broad open fields lie iinsheltered by any
windbreak, the clearing west aud northwest winds
which follow storms not only rapidly dr^- out the soil,
but often sweep entirely away crops of graiu after
they are 4 inches high, uncovering the roots by the
removal of 1 to 3 inches of the surface soil. It has
been observed, however, in these districts, that where-
ever there are windbreaks of any sort, even such slight
barriers as fences and even fields of grass, a marked
protection against drifting has been experienced for
several hundred feet to the leeward of them.
In the case of groves, hedgerows, and fields of
grass, the protection results partly from their ten-
dency to render the air which passes across them more
moist, and partly by lessening the surface velocity of
Lesffetiiny Desindfive Ejjerts of ]l'//((/.s 169
the wind. The writer has observed that when the
rate of evaporation at 20, 40, and 60 feet to the lee-
ward of a grove of black oak 15 to 20 feet high was
11.5 CO., 11.6 e.e., aud 11.9 e.c., respectively, from a
wet surface of 27 square inches, it was 14.5, 14.2 aud
14.7 e.c, at 280, 300 aud 320 feet distant, or 24 per
eeut greater at the three outer stations thau at the
nearer ones. So, too, a scanty hedge- row produced
observed differences iu the rate of evaporation as fol-
lows, during an interval of one hour :
At 20 feet from the hedge-row the evaporation was 10.3 e.e.
At 150 " '' " " " " " 12.5 e.e.
At 300 " " " " " " " 13.4 e.c.
Here the drying effect of the wind at 300 feet Avas
30 per cent greater than at 20 feet, aud 7 per cent
greater than at 150 feet from the hedge.
Then, too, when the air came across a clover tield
780 feet wide the observed rates of evaporation were :
At 20 feet from clover 9.3c.c.
At 1.50 " " " 12.1 e.c.
At 300 " " " 13 e.c.
Or 40 per cent greater at 300 feet away than at 20 feet,
and 7.4 per cent greater than at 150 feet.
The protective influeuce of grass lands, and the dis-
advantage of very broad fields on these light lands,
was further shown by the increasiuglj^ poorer stand of
young clover as the eastern margin of these fields was
approached, even wheu the drifting had been inappre-
ciable. Below are given the number of clover plants
170 Irrigation and Drainage
per equal areas on three different farms as the distance
to the eastward of the grass fields increased : No. 1, at
50 feet, 574 plants; at 200 feet, 390 plants; at 400 feet,
231 plants. No. 2, at 100 feet, 249 plants; at 200 feet,
277 plants ; at 400 feet, 193 plants ; at 600 feet, 189
plants ; at 800 feet, 138 plants ; and at 1,000 feet, 48
plants. No. 3, at 50 feet, 1,130 plants; at 400 feet, 600
plants; at 700 feet, 543 plants.
In these cases the difference in stand appears to
have resulted from an increasing drying action of the
wind. On most of the fields, the destructive effects
of the winds were very evident to the eye, and aug-
mented as the distance from the windbreaks increased.
It appears from these observations, and from the
protection against drifting which is afforded by grass
fields, hedgerows, and groves, that a system of rotation
should be adopted, on such lands, which avoids broad,
continuous fields. The fields should be laid out in nar-
row lands, and alternate ones kept in clover or grass.
Windbreaks of suitable trees must also have a beneficial
effect upon the crops when maintained along fields, rail-
roads, and wagon roads in such places as have been
described, and especially in the prairie sections of the
sub-hamid regions, where irrigation cannot be prac-
ticed. It is, of course, true that trees on the margins
of fields sap the soil in their immediate vicinit}', and
thus reduce the yield there ; but it seems more than
probable that in open, windy sections their protective
influence, which it has been shown they exert, will
much more than compensate for this where there is a
general deficiency of soil moisture.
CHAPTER IV
THE INCREASE IN YIELD DUE TO IRRIGATION IN
HUMID CLIMATES
In order to know how important the right amount
of soil moisture, applied at the right time, is, and in
order to know whether it will pay to irrigate in humid
climates, it is necessary to learn what yields are possi-
ble under the best conditions when the crop must
depend upon the natural rainfall, and, side by side
with these in time and place, to measure the possible
increase in yield due to irrigation, if any there be.
When the stud}' of the importance of soil moisture,
and the principles underlying the methods of saving
and utilizing it, were begun at the Wisconsin station
in 1888, it very early became evident that, in order to
learn just how important it is in plant culture to con-
serve the soil moisture, some method must be adopted
which would permit of giving to the plants under inves-
tigation aU the water they can use to advantage.
This led to the series of experiments which have been
recorded in the introductory chapter, aiming to meas-
ure the amount of water which different cultivated
plants can use under the conditions of field life. But
when the results attained under the methods there used
showed that such large yields are possible, it became
(171)
1(2 Jrr'ujdtioii (iiid Drainage
important to suppleineut the rainfall under wholly
normal field conditions, to see if there would then be
any notable increase over the yields produced under
the natural field conditions. This led to a series of
experiments to be conducted parallel with those on till-
age, to learn how far short of possible yields our actual
ones are when secured under the best moisture relations
at our command ; and irrigation experiments as checks
on our tillage experiments were begun, the results of
which it is important to state.
lu conducting these control experiments on irriga-
tion, the aim has been to treat the cro]) growing under
the conditions of the normal rainfall and under those
of the rainfall supplemented by irrigation, exactly
alike in every way until it became apparent that more
water might be used with advantage, when water was
applied to the control plots as often as it seemed de-
sirable. Xo other elements of difference have been
introduced than those growing out of applying the
additional water.
IMPORTANCE OF THE AMOUNT AND DISTRIBUTION OF
W\\TER IN POTATO CULTURE, AND THE ADVANTAGE
OF IRRIGATION IN CLIMATES LIKE WISCONSIN
There have been two seasons' work with this crop, 1896 and
1897, and both years the potatoes have been planted in rows 30
inches apart and in hills 15 inches in the row, or else twice that
distance. The ground in each ease was given a good dressing of
farmyard manure, plowed in 6 inches deep. Large tubers were
nsed for seed, cut two eyes to the piece, and planted with hoe
about 3 inches deep, and the ground harrowed after planting.
Increase of Potxito Crop hy Irrigation 173
The Eural New-Yorker has been the chief variety grown, but
each year an unnamed variety of the Burbank type has been used
to finish out the piece.
The potatoes were planted about the middle of May each year,
Fig. 26. Differeuce in yield between Rur;;l New-Yorker potatoes,
irrigated and not irrigated, in ISOO.
Fig. 27. Difference in yield between potatoes of Bnrbank tj-pe irrigated
and not irrigated, in 1896.
.^iiiP^^^SSS^^ ^ -^ y?^^^i^l^^#^!S^^^:
'^t:Z^^^
"^J^gf^A-J.
1
Fig.
28. Difference in jdeld lietween Rural New-Yorker potatoes,
irrigated and not irrigated, in 1897.
and given flat cultivation after every rain, or oftener, until the
vines were so large as nearly to cover the ground, when they were
hilled with a double shovel plow drawn through the center of each
row, forming ridges about 5 inches high, the nose of the shovel
passing about 3 inches below the surface of the ground.
174
Irrigation and Drainage
The amounts of rainfall and of water applied by irrigation are
given in the table below :
Rainfall .
Wa
er of irngation
1896
1897
1896
1897
INCHES
INCHES
INCHES
INCHES
May...
. 6.11
.51
May ....
May.
June...
. 2.25
4.03
June
June
July...
. 3.42
1.7S
July 10..
. 2.15
July 20....
2.45
Aug. ..
. 2.43
3.7
July 21..
. 2.15
Aug. 18 . . .
2.45
Sept...
. 3.73
1.73
Aug. 3 ..
Ang. 10 .
. 2.15
. 2.15
Sept. 8 . . . .
2.45
17.94
11.76
Sept. 3..
. 2.15
Sum.
10.75
7.35
The distribution of the rainfall during the season can be
learned from the table given on page 108. It will be seen that in
1896 the irrigated potatoes had 10.75 inches, and in 1897 7.35
inches, more water than the potatoes grovm under the natural
rainfall conditions. "
These differences in the amount of water produced differences
of yield, which are shown below in the table, and graphically to
the eye in Figs. 26, 27 and 28. To eliminate the effects of varying
soil conditions, the water was applied to alternate groups of 6 to
10 rows, with corresponding intervening groups of rows which
received no water. There were 16 of these plots in 1896 and 22
in 1897, making 38 trials in all, in which there were grown a total
of 555 bushels of potatoes, or 33,304.4 pounds.
Table showing yield per acre of potatoes irrigated and not irrigated in
WisconMn
1896
1897
1896
1897
Mean
Difierence 105. S
RUKAL NeW-YORKEE
T • t 3
. Not irrigated
Large Small
Large Small
BU. BU.
BU. BU.
382 12.2
280.3 10.2
365.8 9.1
239.6 9.7
BUEBANK TTPK
220 22.7
141.5 16.2
302 16.8
181.9 19.75
317.5 lc.2
2U.e H
Increase of Cabbage Croj) by Irrigation 175
There is thus shown a difference of 105.9 bushels of merchant-
able tubers per acre, as an average of two yeai's, in favor of the
larger water supply.
EFFECT OF SUPPLEMENTING THE RAINFALL IN WIS-
CONSIN FOR CABBAGE CULTURE
In the work with cabbage, the rows were set 30 inches apart,
and in half of the area the plants were set 15 inches apart in the
row, and on the balance of the area 30 inches apart, of the variety
Fottler's Drumhead. There were, in all, 22 alternating plots of 6
rows each, one half irrigated and the balance not. The soil was
a rather heavy clay loam, which had been heavily manured the
previous year, and had grown a crop of cabbage and cauliflower,
but nothing was added this season. Flat and frequent cultivation
was given until the plants were large and nearly covered the ground,
July 21, when the first irrigation was made, the irrigated rows
being furrowed the same as the potatoes, and not again disturbed.
The mean weight of heads produced under the two treatments
was as follows :
/ Thin planting ■ Thick planting .
Irrigated Not irrig. Irrigated Not irrig.
LBS. LBS. LBS. LBS.
Firm heads 7.6 6.95 5.13 4.46
Loose heads 4.88 4.33 3.23 2.39
The weight of the heads dressed for market, computed for one
acre, was as expressed in the following table:
' Thin planting . Thick planting — -
Irrigated Not irrig. Diflf. Irrigated Not irrig. Diff.
LBS. LBS. LBS. LBS. LBS. LBS.
Firm heads 30,610 29,480 1,130 46,590 40,100 6,490
Loose heads 6,227 4,624 1,603 7,688 5,943 1,745
Total 36,837 34,104 2,733 54,278 46,043 8,235
Leaves and stumps.. 42,730 39,220 3,510 64,100 57,630 6,470
Grand total.... 79,.567 73,324 6,243 118,378 103,673 14,705
Tons 39.78 36.66 3.12 58.19 5L84 7.35
176
Irrujatloi and Drainage
The amount of water given to this crop was 8.245 inches, in
four applications, July 21^ Aug. 3 and 10, and Sept. 3, 2.061
inches being applied each time.
The difference between equal numbers of rows of cabbage
irrigated and not irrigated is shown in Fig. 29. "Were the cabbage
grown for green fall and early winter feed for stock it will be seen
that the close setting gives a difference in favor of irrigation
Fig. 29. Diiferenee in j'ield between cabbage, irrigated and not irrigated.
amounting to 7.35 tons per acre. This occurred, too, under con-
ditions in which the plots not irrigated received considerable
water from seepage from the heavy irrigation of a piece of
meadow.
The same season that these experiments were made with cab-
bage, similar ones were conducted with mangold-wurzels and with
turnips. But while a good yield of beets was secured per acre,
namely, 15.7 tons, there was only 18 pounds difference, the six
rows of irrigated mangolds yielding 5,100 pounds and those not
irrigated 5,082 pounds. The turnips, on account of a blight,
did nothing under either treatment, and the same was true foi
rape.
THE EFFECT OF SUPPLEMENTING THE RAINFALL WITH
IRRIGATION ON THE YIELD OF CORN
During four consecutive years we have grown com upon one
area, irrigating a part and reserving another part not irri-
gated, as a check. The soil of this plot is medium clay loam.
Increase of Corn Crop by Irrigation 111
Just before beginning the experiments it had been in clover, and
was dressed with farmyard manure at the rate of 44 loads per acre
before plowing, in the spring of 1894. Since this time it had re-
ceived no manure or fertilizers of any kind, one object of the
experiment being to ascertain whether under irrigation the land
rapidly deteriorates in productiveness.
Each season the corn has been planted very close, in rows 30
inches apart and in hills 15 inches in the row, working upon the
hypothesis that when an abundance of water is supplied more
plants may be grown upon the same area, the hypothesis having
been suggested by the large yields universally secured in the
experimental cylinders.
The number of stalks in a hill has varied, but usually as
many as 3 to 5 stalks have been allowed to mature. Both flint
and Pride of the North dent corn have been grown each year,
and one season a part of the area was planted with rows 36
instead of 30 inches apart. The table which follows gives the
yields of water-free matter per acre, together with the rainfall of
the growing season and water added by irrigation:
Not Irrigated
Irri
i gated
Difference
Kind
of corn
Water
used
Dry
matter
Water
used
Dry
matter
Water
used
Dry
matter
INCHES
LBS.
INCHES
LBS.
INCHES
LBS.
Flint
Dent
8.15
7,916
7,426
16.76
11,080
9,625
8.61
a, 164
2,lfl9
Flint
Dent
4.48
2,458
3,144
31.08
10,048
11,125
26.6
7,590
7,981
Flint
Dent
15.02
8,129
8,4.50
27.07
10,320
10,280
12.03
2,191
1,830
Flint
Dent
10.66
6,766
C.853
16.36
8,571
8,438
5.7
1,805
1.585
It will be seen, from the data of this table, that there has been
during the four years a mean gain due to the increased water sup-
ply amounting to 3,543 pounds of water-free substance, while the
mean yield under the season's rainfall with the best of tillage has
been 6,393 pounds per acre, or an increase of 55 per cent. The
smallest mean gain realized in any year has been 24.9 per cent
and the largest 278 per cent.
178
Irrigation and Drainage
In Fig. 30 is shown the diflference between the corn on land
irrigated and not irrigated in 1895, when there was the largest ob-
Fig. 30. Difference iu j-ield between maize, thickly seeded, irrigated
and not irrigated, in v. dry season.
served difference in the yield. Fig. 25 shows the difference where
the rows are 44 inches apart instead of -JO inches, as in the former
case.
THE EFFECT OF SUPPLEMENTING THE RAINFALLL WITH
IRRIGATION ON THE YIELD OF CLOVER AND HAY
The crop of hay is, perhaps, the one above all others among
the general farm crops which may be made to respond most effec-
tively to irrigation in humid climates. Indeed, it is the chief one
in Europe which has been grown by irrigation north of Italy
Iv crease of Hay Crop by Irrigation 179
and southern France. Reference has already been made to
water meadows.
We have shown in another place that the average yield of hay
per acre in thirteen states in this country was, for 1879, only 1.1
tons. It is true, however, that good soils, well managed, may be
made to yield most years an average of possibly 1.5 tons per acre.
There will be seasons, however, for these soils when the yield will
drop back to 1 ton per acre. Again, those seasons are rare for
most soils in the United States which will permit them to produce
three -fourths of a ton of hay per acre as a second crop without
irrigation.
Our experiments in irrigating clover for a second crop gave
1.798 tons, 2.035 tons, and 1.773 tons of hay, containing 15 per
cent of moisture, for the years 1895, 1896, and 1897 respectivelj'.
In irrigating the first crop of clover, the yields have been 4.01 tons
per acre, in a case of sub -irrigation through tile drains in 1895,
and 2.671 and 2.65 tons in 1897, which were surface irrigated,
making an average for the two crops of 4.979 tons of hay per acre
so thoroughly cured as to contain 85 per cent of dry matter.
These results, it should be understood, are derived by making an
actual determination of the dry matter in each crop and comput-
ing the weights of hay from the amount of drj' matter.
It will be observed that these yields are more than four times
the mean yield of the thirteen states cited in another place. In
addition to the first and second crops, there has been each time an
excellent third crop, which could be used for fall pasture, and
easily double in quantity the non- irrigated fall feed of the best
seasons. Fig. 31 is a view of the second crop of 1895, the third
crop on the same ground, giving pasture for 58 adult sheep 31 days
on 3.2 acres.
A CROP OF BARLEY AND A CROP OF HAY THE
SAME SEASON
In the spring of 1897 we seeded a piece of ground to clover
with barley, irrigating a part of the barley twice, both to see what
the effect would be upon the yield of barley and upon the clover
180
Irrigation and Drainwje
whieh had been sown with it. It so happened that immediately
after each time of irrigating tiie barley a good rain followed, and
the difference in jueld of grain and straw per acre was small, as
stated below:
Irrigated Not irrigated Difference
Air-dry straw— lbs 5,Tc!5 5,133 C02
Air-dry grain — bit 45.67 44.25 1.42
But the effect on the clover was very marked. In order to
bring np tiie clover on the areas not irrigated, the ground was
Fig. 31. Second crop of clover hay on irrigated groujid.
irrigated immediately after cutting the barley, July 23. Two other
irrigations were given the ground, and as a result there was a crop
of mixed clover and barley, cut on Sept. 22, which equaled 1.36
tons of hay. The barley cut with the clover resulted from the
germination of seed whieh shelled in harvesting the grain, and
was just heading out when it was cut to put into the silo.
It is very evident, from these results, that it will be possible
Increase of i:it)iaU Fruit Crop hi/ Irrigation 181
to seed clover with either oats or barley, and by cutting the first
crop early for hay and then irrigating, a second crop of hay equal
at least to one ton per acre may usually be t^ken, besides making
it certain that a good stand of clover is secured for the next year.
THE EFFECT OF SUPPLEMENTING THE RAINFALL FOR
STRAWBERRIES
The strawberry is a crop which will respond in a marked man-
ner to judicious applications of water in most parts of the United
"States suited to its growth, as the results secured at this station
by Professor Goff clearly show. His yields per acre were:
Irrigated Not irrigiited Difference
BU. BU. BU.
1894 214.6 109.3 105.3
1895 272.9 32.2 240.7
Mean 243.8 70.8 173
It is here seen that the irrigated yield was more than three
times as large as that under natural rainfall conditions ; and not
only was the yield this much larger, but the quality of the berries
was also improved by the irrigation, they being larger and more
salable.
While we are able tu cite no critical data regarding the
advantage of irrigation in humid climates on blackberries, rasp-
berries, currants and gooseberries, the unquestioned fact that these
do very frequently suffer severely from the effects of drought
leaves no room to doubt that these, like the strawberries, would
be greatly benefited by irrigation in very many seasons.
CLOSER PLANTING MADE POSSIBLE BY IRRIGATION
It lias been pointed out that in sub -humid climates
the limiting factor which determines the number of
plants which may develop to advantage in a given soil
is the amount of available moisture ; but that in coun-
182 Irrigation and Drainage
tries where there is an abundant and timely distrib«tiou
of rain, or where irrigation is practiced, the number
of plants per acre may be so far increased that the
limiting factors become the available plant-food stored
in the soil, the amount of sunshine which falls upon
the area, or the circulation of air about the assimilat-
ing foliage.
It is very evident that were the amount of available
water for crop production the only factor which de-^
termines the number of plants which can be grown per
unit area, the methods of irrigation would make it pos-
sible to greatly increase the yield of almost any crop
in the most humid of climates. But there are many
limiting factors which set rigid bounds beyond which
irrigation may not pass.
{Sufficient breathing room in the soil. — Since the roots
of all cultivated plants demand free oxygen in the soil
for their respiration, and since not only the possible
quantity of free oxygen in the soil, but the rate at
which it may be supplied, decreases as the quantity of
water in the soil increases, and since the closer the
plants are set upon the ground the more densely crowded
must the roots be in the soil, and the more rapid must
be the interchange of gases between the soil and the
air above in order to meet the increased demands for
growth, it is plain that the demand for free oxygen in
the soil sets a rigid limit beyond which closer planting
must not be pushed.
It must be kept ever in mind that the soil is like a
very poorly ventilated assembly hall, which may easily
be so crowded as not only to produce discomfiture to
Factors Limitiitg Closeness of Flauting 183
its occupants, but disaster as well. Nor do the roots
of the plants which occupy the field constitute the only-
demand for free oxygen in the soil, for the various
fermenting" germs which transform humus into avail-
able nitrates must have free oxygen, or the all-
important nitric acid cannot be made, and the farm-
yard manures applied to the soil must lie there unal-
tered and of no avail.
Soiliemperature reduced by too close planting . — Then,
again, too heavy verdure above the soil so completely
absorbs the heat from the surrounding air and dissi-
pates it again into space, that the soil temperature can-
not rise high enough to produce the maximum rate
of solution and production of plant -food, nor the
maximum root pressure so essential to sending the dis-
solved and prepared food into the foliage above, where
assimilation takes place ; while the humus aud ma-
nure-fermenting germs themselves must work the slower
the lower the soil temperature is after it falls below
98° F. It is true that available nitrates may be applied
to the soil direct, and other of the ash ingredients in
soluble form may be added, or the soil may receive
thorough and lepeated tillage before the crop is put
upon it, and thus a supply in advance be generated,
which leaves more of the oxygen and of the soil warmth
for the service of the roots; but neither of these con-
ditions can be attained except at added cost.
The sunshine itself is limited. — Even when we come
to the item of sunshine itself, it is easy to so increase
the number of plants that not enough sunshine can be
absorbed to produce normal growth, and a diminished
184 Irrigation and Brainaye
yield or inferior quality results. The taller the plants
which are brought togethe-r, the farther apart as a
rule must they be placed, in order that sufficient sun-
light for the best results can be had. The flint varie-
ties of maize are readily grown closer together than the
smaller of the dent varieties, and these, in their turn,
may stand closer on the ground than the large southern
varieties.
Neither the starches nor the cellulose out of which
plant tissues are built can be properly organized and
laid down in too feeble a light, for its actinic power is
demanded to accomplish this work, just as it is in pho-
tography. When it is remembered that an instanta-
neous exposure of a plate in the bright sunshine may
accomplish more chemical change in the negative than
can be done in two minutes in the diffused light of a
well-lighted room, it can be readily understood that the
work of assimilation in the lower leaves in close plant-
ing must be greatly enfeebled.
It is for this reason, apparently, that ears will not
form on stalks of maize planted too closely, and that
they form more abundantly in closer planting on the
small, low varieties than on those which are taller.
It is for the same reason, too, that too closely
planted crops of almost any kind have weak stems and
are unable to stand up well, often lodging ; neither the
starches for the kernels, in the former case, nor the
cellulose in the latter for the building of the frame-
work, are able to form rapidly, and abnormal growth
is the result. Whoever has entered and emerged from
a tunnel has been surprised at the short distance from
Factors LimitiiKj Closeness of Planting 185
the mouth at which the tunnel becomes dark ; the re-
peated reflections from the walls soon absorb completely
all of the light which enters. It is the same way with
close planting, especiall.v if the individuals are tall, the
vipper parts of the tall plants absorbing just as
much light as the same length of shorter plants, hence
leaving less light to work in the foliage aud stems of
the lower parts.
Possible insufficiency of carhon dioxide in close
jylanting. — When a crop like maize, which grows so
tall and spreads its leaves so broadly, is planted closelj"
it seems not impossible that on days of exceptionally
bright sunshine and when very little wind is moving,
there may be such rapid consumption of carbon dioxide
from the air as to so far reduce its amount that an
inadequate supply may actually reach the plants.
It has been shown on a preceding page that a clover
crop yielding 4,500 pounds of hay per acre demands
for its carbon all of the carbon dioxide contained in a
layer of uniform density covering the acre 3,503 feet
deep. But in the case of a corn crop, in which the yield
of water-free matter has exceeded 14,000 pounds, the
volume of air required to give up its carbon dioxide
must have exceeded that above more than threefold,
or a column of uniform density exceeding 10,509 feet
in height. Fully 80 per cent of this assimilation of
carbon by the corn plant must take place in the 50
days following July 1. Imagine, if you will, a field of
corn 160 rods long and 1 rod wide, enclosed by a
transparent structure having the same floor space and
rising to a height of 10,000 feet, so as to enclose the
186 Irrigation and Drainage
volume of air stated above. Now, let this structure be
provided with a ceiling without weight, which is lifted
as the corn grows in height. This imaginary ceiling is
to separate the volume of air stored above from the
moving air in the corn field below, and to admit
through a changing doorway a steady stream whose
cross -section is that of the transverse section of the
room occupied by the corn. How rapidh* must this
stream of air flow in order to discharge 80 per cent of
the volume contained in the structure in the sunshine
hours of 50 days '? The maximum number of sunshine
hours in the latitude of New York is about 623. If we
suppose the corn to be 1 foot high July 1 and 10 feet
high on August 19, the ceiling to have risen uniformly
in the meantime, so that the stream of air increased in
depth from 1 foot to 10 feet ; then, taking the mean
depth of the moving air current at 5.5 feet, its hourly
velocity, in order to convey the 80 per cent of air
across the field, must have been 1.167 miles. On the
other hand, let us suppose the corn field to be square,
so that the area is as compact as possible, so that a
stream of air now about 13 rods wide instead of 1 is
passing across it. The required velocity to convey the
80 per cent of air across the field is now only one-
ninth of a mile per hour and less than 10 feet per
second. Since the yield of dry matter per acre is the
largest we have yet raised under field conditions, and
the computed velocities above are so small, it does not
appear likeh' that an insufficiency of carbon dioxide in
the air can ever be a serious limiting factor to the
closeness of planting when irrigation is practiced.
Maximum Limit of Productiveness for Maize 187
MAXIMUM LIMIT OF PRODUCTIVENESS FOR MAIZE
In order that some idea of the possible maximum yields of
maize per acre might be formed, we have gone into the field,
when the corn was mature, and selected 40 of the largest stalks
bearing the largest ears we could find, and have determined the
water-free matter in both ears and stalks, in order to secure a
measure of the mean maximum adult plant to use as a basis of
computation for this problem. The results were these:
40 stalks of Pride of the North maize contained 15.6 lbs. water-free substance.
40 ears " " " " " " 16.1
40 " " " " " " " 13.7 " shelled corn.
40 " " " " " " " 2.4 " cobs.
Using these data, we may compute the maximum possible
yields per acre where different degrees of closeness of planting are
adopted, supposing that every plant produces a maximum-sized
stalk, bearing a maximum ear corresponding with the data above.
Then maize planted in hills 4 feet x 4 feet, and 4 stalks in a
hill, or in drills 4 feet x 1 foot, might yield 8,630 pounds dry mat-
ter, 3,730 pounds kiln-dried shell corn, equal to 66.61 bushels, or
73.27 bushels when containing 10 per cent of moisture.
With maize planted in hills 44 inches x 44 inches, 4 stalks in
a hill, or 44 inches x 11 inches in drills, the maximum yield per
acre would be 10,270 pounds dry matter, 4,439 pounds kiln-dried
shelled corn, equal to 79.27 bushels, or 87.2 when containing 10
per cent of moisture.
Maize planted 42 inches x 42 inches, 4 stalks in a hill, or in
drills 42 inches x 10.5 inches, might yield 11,270 pounds of water-
free matter and 4,871 pounds of kiln-dried shelled corn, equal to
87 bushels, or to 95.7 bushels when containing 10 per cent of
moisture.
Maize planted 36 inches x 36 inches, 4 stalks in a hill, or in
drills 36 inches x9 inches, might yield 15,340 pounds of dry matter
and 6,600 pounds of kiln-dried shelled corn, equal to 118.4
bushels, or to 130.27 bushels when containing 10 per cent of water.
188 Irrigation and Drainage
Maize planted 30 inches x 30 inches, 4 stalks in a hill, or 30
inches x 7.5 inches in drills, might yield 22,090 pounds of dry-
matter per acre and 9,574 pounds of kiln-dried shelled corn,
equal to 170.4 bushels, or 187.44 bushels containing 10 per cent
of water.
Maize planted 30 inches x 15 inches, 4 stalks in a hill, or in
drills 30 inches x 3% inches, might yield, if every stalk equaled the
average of the 40 stalks cited above, 44,180 pounds of dry matter
per acre and 19,148 pounds of kiln-dried shelled corn, equal to
340.8 bushels, or 374.88 bushels when containing 10 per cent of
moisture.
Some of the yields here computed have been realized under
field conditions, but the higher ones never have been and prob-
ably never can be, under any system of culture as a single crop.
In our experimental work with the large cylinders, the largest
yield we have obtained was 34,730 pounds of water-free sub-
stance when 4 stalks occupied a soil space of 1.767 square feet,
which is closer planting than the closest given above, namely
rows 30 inches apart, with corn in drills, stalks 1% inches apart.
The largest yield we have secured in the field was on an
area of irrigated ground measuring about 2,400 square feet, where
the amount of dry matter per acre was 29,000 pounds, or 14,5
tons. In this case, the corn was planted in rows 30 inches apart
and in hills 15 inches apart, with 3 to 5 stalks in a hill. The area
was not an isolated plot, but was a selected spot in an irrigated
area where, on account of a sag in the ground, the corn had
received more than the average amount of water. The closeness
of planting in this case was equivalent to drilled rows with 1 stalk
every 3% inches, which is the same as the closest given above,
but the corn was a variety of flint maize, not dent.
THE OBSERVED YIELDS OF MAIZE PER ACRE PLANTED
IN DIFFERENT DEGREES OF THICKNESS AND WITH
DIFFERENT AMOUNTS OF WATER
It has been possible, with our irrigation, to make a direct test
of the influence of the amount of water on closeness of planting
Maximmn Limit of Production for Maize 189
maize, and thus to demonstrate whether, with the aid of irriga-
tion, it will be possible in humid climates to secure larger yields
by planting closer together.
The problem this year has been tested with two varieties of
maize, Pride of the North, and a white dent of unknown name.
Each has been planted in rows 44: inches apart and in hills 15
inches in the row. The white dent was thinned to 4 stalks, 3
stalks, 2 stalks, and 1 stalk in a hill, and the Pride of the North
to 3 stalks, 2 stalks, and 1 stalk in a hill. It was found, after the
stalks had attained some size after thinning, that the white dent
threw out 1 and sometimes 2 suckers where it had been thinned
to 1 stalk. These were allowed to stand, rather than incur the
risk of introducing greater irregularities which would be unknown.
But few of these suckers matured ears, and hence their effect has
been to increase the amount of stalk in proportion to the ear, and
possibly even to reduce the weight of ears, particularly on the
ground not irrigated. The Pride of the North was planted on
ground from which hay had been cut three consecutive years, and
in which a fair amount of clover was maintained, the land having
been irrigated. The white dent was grown upon ground from
which two crops of cabbage had been taken, and which had been
irrigated for both crops. Preparatory to planting the first crop of
cabbage, after turning under the clover sod, the gi-ound had been
given a dressing of partly rotted stable manure amounting to 68
tons per acre. In addition to this, a mixture of commercial fer-
tilizers consisting of 157 pounds of bone meal, 25 pounds Armour's
"all soluble" fertilizer and 6 pounds of nitrate of soda was sown
broadcast upon the ground Aug. IG. Neither manure nor fertil-
izers of any kind were given to the soil of either piece for tho
season the corn was grown nor the year before.
In both cases the corn was harrowed before coming up, and
cultivated twice in a row until too large to work longer. The
several areas bearing corn of different degrees of thickness were
divided into three sub-plots, and the middle one in each case was
not irrigated, while the two adjacent ones were.
At maturity the corn was husked, and the amount of water-
free substance in both ear and stalk determined in each case.
190
Irrigation and Drainage
The photo -engravings, Figs. 32, 33, 34 and 35 (pages 192, 193),
s'how the relative amounts of corn husked from each plot and the
areas upon which these were grown, while in the table below are
given the yields per acre:
White Dent
4 stalks
Dry
2 stalks
Dry
matter
per acre
LBS.
Shelled
corn
-— 1 stalk
Dry
matter
per acre
LBS.
Shelled
corn
BU.
11,426
53.44
12,567
Corn Irrigated
63.23 11,712
66.01
9,554
Corn not Irrigated
8,758 30.38 9,126 39.45 7,931 48.66 7,354 39.03
Difference in Yield
2,668 23.06 3,441 23.78 3,181 17.35 2,200 10.5
In the ease of the Pride of the North, the corn was planted
3 stalks, 2 stalks, and 1 stalk in a hill, and the yields in this case
were as follows :
Pride of the North Dent
. 3 stalks .
' 2 stalks .
1 stalk-
,
Dry matter Shelled
Dry matter Shelled
Dry matter
Shelled
per acre corn
per acre corn
per acre
corn
LBS. BU.
LBS. BU.
LBS.
BU.
10,265
45.20
Corn Irrigated
11.350 69.62
Corn not Irrigated
9,328 47.79
Difference
2,022 21.83
8,944
8.536
55.29
It will be seen from these tables that the yield of water -free
substance per acre was largest in every case where the corn was
planted 3 stalks in a hill every 15 inches, and in rows 44 inches
apart. It is a significent fact that this is true, not only with both
Yields of Maize until Irrigation 191
varieties of corn, but also where the corn was irrigated and where
it was not irrigated. It will be seen, further, that the smallest
yield of dry matter per acre was produced where the smallest
amount of seed was used, namely, where 1 stalk grew every 15
inches ; but one-third the number of plants produced about three-
fourths as much dry matter per acre as did the larger number of
plants.
It must be understood, however, that so far as mere water
is concerned, the thinnest planting had decidedly the advantage,
as no effort was made, even on the ground irrigated, to make
the water applied proportional to the number of plants and, there-
fore, to the evaporating surface. Whether making the amount
of water proportional to the number of plants would have materi-
ally increased the yields of the ^thicker seeding, is a problem
which awaits demonstration. Indeed, we do not, as yet, know
that the thinnest seeding had all of the water which could be used
to advantage, even where irrigation was practiced. But the fact
that the smaller variety of maize. Pride of the North, the one
which produced no suckers, and, therefore, the one which more
nearly represented 1 stalk every 15 inches, only gave an increase
of 408 pounds of dry matter per acre for the 7.642 inches of water
added by irrigation to the rainfall of 10.66 inches, appears to show
that this corn found in the 10.66 inches of rain nearly all the
water it could use to advantage. This view is strengthened,
also, by the fact that the theoretical yield of dry matter per
acre for the maize, computed from the data in the table on
page 187, is 8,848 pounds, only 312 pounds more than was
observed.
Looking at the yield of kiln -dried shelled corn per acre, it
will be seen that here a somewhat different relation holds, the
largest crop with the white dent variety being secured from 2
stalks in a hill every 15 inches ; but with the smaller variety of
Pride of the North the largest yield of shelled corn coincided
with the 3 stalks in a hill where irrigation was practiced ; but
where the natural rainfall alone produced the crop, the largest
yield was associated with the thinnest seeding, or ] stalk every
15 inches in the row. It is a noteworthy fact, too, that the 7.642
192
Irrigation and Drainatje
inches of water added by irrigation only increased the grain yield
3.64 bushels per acre on the thinnest seeding, appearing to show
Fig. 32. Maize, irrigated and not irrigated, four stalks in a hill,
middle section not iirigated.
that for this soil and rainfall there was very nearly the right num-
ber of plants in the row.
Fig. 33. Maize, irrigated and not irrigated, three stalks in a hill,
middle section not irrigated.
In regard to the yields from the thicker seeding, it must be
said that it does not follow from the experiments that the\- might
not have been quite different if, in the application of water to the
several plots, the amounts had been made proportional to the
number of plants growing on the area ; for it may fairly be pre-
Influence of Thick Seeding on Development 193
sumed, until positive demonstration shall prove to the contrary,
that in ease there was a deficiency of soil moisture for the thick
rig. 34. Maize, irrigated and not irrigated, two stalks in a hill,
middle section not irrigated.
seeding, a larger supply would have increased the yield of shelled
corn as well as the total amount of dry matter.
Pig. 35. Maize, irrigated and not irrigated, one stalk in a hill,
middle section not irrigated.
INFLUENCE OF THICK SEEDING AND IRRIGATION ON
THE DEVELOPMENT OF THE PLANT
It was observed, the first year the maize was planted thickly
and irrigated, that the com did not appear to develop quite nor-
M
194 Irrigation and Drainage
mally, the tassels coming into bloom before the silks were ready to
receive the poDen, and it looked then as though the failure to
develop the normal amount of ears might result from this ab-
normal development, in time, of the staminate and pistillate
flowers.
The facts are that very few kernels at all formed on the non -
irrigated dent variety, and only imperfect ears matured on the
flint variety ; while on the irrigated plots vei-y many ears never
filled at all, and with many of those which did develop ears, the
kernels did not cover the entire cob, it being very often observed
that no kernels at all formed at the butt of the ear, and sometimes
none even half way to the tip. Whether the thick seeding and
rapid growth stimulated by irrigation retards the development of
the ear by shading, or overstimulates the maturing of the tassel
so as to interfere with the proper fertilization, cannot be decided
from data yet at hand, although the appearance of the plants
looks veiy much as though such an abnormal development had
been brought about.
The nodes of the stalks are certainly lengthened by the close
planting and irrigation practiced, but not all are equally affected.
If it is true that a certain intensity of sunlight is required for the
proper maturing of the ear, it might be anticipated that the effect
of the shading would stimulate a greater elongation of the lower
than of the upper nodes of the stem, thus placing the ear in more
intense light. To ascertain whether any such change as this had
occurred, measurements were made of 40 stalks of irrigated thick
planting, and a corresponding number of plants not so closely
planted and not irrigated, of Pride of the North dent, with the
result that in the non-in-igated com the height of the axil bear-
ing the ear was 46.82 per cent of the height from the ground to
the base of the tassel ; while that of the irrigated com was 55.2
per cent of the height. That is to say, the ear axil in the thickly
planted irrigated com was raised 8.38 per cent nearer to the
tassel.
In a second set of measurements, with the same variety of
corn, the height of the axil bearing the ear was 49.44 per cent of
the height of the tassel above the ground, while under the condi-
Influence of Thich Seeding on Development 195
tions of irrigation the height of the axil was 56.94 per cent of the
height of the tassel, making a difference in this ease of 7.5 per
cent in the same direction. In the case of a variety of flint com,
however, the conditions are the reverse of those just cited, the axil
bearing the ear being 41.16 per cent of the height of the tassel,
while on the ground irrigated this height is 39.59 per cent of the
height of the tassel above the ground. The ease is, therefore, not
without exception as tending to show that the deficiency of light
modifies the plant in the manner pointed out.
CHAPTER V
THE AMOUNT AND MEASUREMENT OF WATER REQUIRED
FOR IRRIGATION
There is no problem of greater or more fundamen-
tal importance to the irrigator than that which deals
with the amount of water required to produce paj'ing
yields when correctly and economically handled in the
production of crops of various kinds. The problem is
an extremely complex one, which has received as yet
very inadequate systematic study on a rational basis,
such as the exigencies of the case demand.
THE MAXIMUM DUTY OF WATER IN CROP
PRODUCTION
A given quantity of water applied to the soil, either
in the form of rain or by methods of u-rigatiou, renders
its greatest service when the whole of it is taken up by
the roots of the crop growing upon the ground, leaving
none to be lost by surface evaporation or by percolation,
unless, indeed, some soil leaching is indispensable to
unimpaired fertility. Were it practicable to establish
and maintain field conditions of culture which would
insure that all water lost from the soil should take
(196)
The Duty of Water 197
place through the foliage of the crop being fed, then a
very small rainfall during the growing season, and a
very small amount of water added by irrigation, would
suffice for the production of large yields.
In other words, the duty of water in crop produc-
tion is determined by the necessary losses : (1) by
transpiration through the plant ; (2) by surface evapo-
ration from the soil ; and (3) by surface and under-
drainage. The more these sources of loss may be cur-
tailed, the larger will be the duty of water in both arid
and humid regions.
In countries where irrigation must be practiced in
order to successfully grow crops, skillful management
may almost wholly prevent loss by drainage, and loss
by surface evaporation from the soil can be made
relatively very small, so that the major loss may
be that which is transpired through the plant itself.
So, too, in humid climates, the losses during the grow-
ing - season by both drainage and surface evaporation
may be greatly reduced through skillful, intelligent
practice.
It will, therefore, be helpful, in forming an estimate
of the possible duty of water, to use the data already
presented in another place to compute the minimum
number of acre -inches of water which may be made to
produce yields of different amounts under the condi-
tions where no drainage takes place, and where surface
evaporation is made as small as it can well be. The
results of such a calculation are given in the table
which follows:
198
Irrigation and Drainage
Table showing the highest probable duty of water for different yields per acre
of different crops
Bushels per acre..
15
20
30 40
50 60
1
70
80
100
200
300
400
Name of crop
Least number of acre-inches of water
Wheat
1
4.5 6
3.21 4.28
2.35 3.13
9
6.42
5.70
5.04
.62
12 15
8.56 10.7
18
12.84 14.98
9.40 10.98
Oats
6.27
6.72
.83
7.81
8.4
1.03
T^.'U
15.68
16.77
2.07
4.14
6.2
Maize
2.52
3.36
.41
10.0811.75 13.43
1.24| 1.45 1.65
3.27
Tons per acre
1 2
3
4
6
8
10
12
14
16
18
20
Least number of acre-inches of water
Clover hay,
15 per ceut water
Corn with ears,
15 per ceut water.
Corn silage,
70 per cent water.
4.43
2.08
1.41
8.85 13.28
4.1G 6.24
2.82 4.23
17.7
8.32
5.64
26.55
12.47
8.46
35.4
16.61
11.28
44.25
20.72
14.1
24.95
16.92
29.1
19.74
33.26
22.56
37,42
25.38
41.58
28.2
This table must be regarded as showing the mini-
mum amounts of water which will bring the crops
named to full maturity so as to produce the yields speci-
fied under conditions of absolutely no loss by surface
or under -drainage, and where the evaporation from the
soil itself is as small as it can well be. It must be
further understood that the soil at seeding time already
possesses the needful amount of water for the best con-
ditions, and that at the end of the growing season it is
yet so moist that no check to vigorous, normal growth
has occurred.
The figures in the table may, therefore, be regarded
Conditions Modifying the BiUij of Water 199
as the nearest estimate now attainable of the minimum
amount of water the irrigator can hope to deliver to his
field where the yields there stated are expected ; and if
there are necessary losses in bringing the water to the
field, either by seepage or evaporation from the main or
lateral ditches, or if the water is badly handled, so that
there is a large amount of percolation ; or, again, if
unnecessary losses occur through lack of proper tillage
after u-rigation, then the amounts stated in the table
must be exceeded by the amount of these losses.
CONDITIONS WHICH MODIFY THE AMOUNT OF WATER
REQUIRED IN IRRIGATION
Among the many factors and conditions which increase or
diminish the duty of water may be mentioned:
1. The pecnUarities of the crop grown. — From what has been
said regarding the amount of water required for a pound of dry
matter and for yields of different amounts for different crops, it
will be evident that both the amount of water required by a
given crop and the frequency with which it should be applied will
depend much upon the crop being grown.
This variation in the amount of water required by different
crops depends upon many factors, some of which are not well
understood. Both the number and size of the breathing pores of
the green parts of the plant, through which the air enters and
from which the moisture escapes, may be expected to play an
important part in determining the necessary loss of water which
takes place. So, too, will the character of the foliage and the
habit of the plant as influencing the amount of wind movement,
and of shade over the soil of the field, effect the necessary loss
of water from the soil.
In illustration of the influence of the shade offered by the
crop upon the loss of water from the soil may be cited the differ-
200 Irrigation and Drainage
ence in the amount of water in the soil of a potato field where
the rows extended east and west, thus producing a shade on
the north side of each row. The samples of soil were taken
June 27. In this ease the rows were planted 3 feet apart, and
the table given on page 161 shows a difference of 4.5 per
cent in the upper six inches on the sunny and shaded sides of
the row.
Then, too, if the roots of the crop do not penetrate deeply
into the soil, more water will be required, for the double reason
that more water is liable to be lost by percolation below the root
zone, and because a greater frequency of water will be required
than if the roots went deeper ; hence, there will be more loss by
surface evaporation.
2. Tlte character of the soil. — In the studies which have been
made regarding the amount of water required for a pound of dry
matter, there has been nothing to indicate that a plant growing
in one soil requires more water than when growing in another,
provided there is always an abundance of plant -food available to
the crop throughout its period of growth. In other words, if it
were possible to avoid losses by seepage, and by evaporation
other than that which takes place through the growing crop, it
does not appear that the duty of water would vary with the
character of the soil.
But, while it is true that by skillful management water may
be distributed, even over the soils of coarse texture, with
little or no waste through seepage, and while surface evaporation
may be very greatly reduced by suitable methods of applying the
water and of tillage, there will always be those living under the
same water supply who are less skillful than others, and who will,
by their lack of skill, require more water in order to secure the
same yields ; and, in consequence of this, the duty of water will
vary to some extent with the soil.
There are really wide variations in the effectiveness of
mulches developed from different soils, and while these are not
as great as the variations in the rates of seepage, the losses of
water through surface evaporation are less completely under con-
trol than those due to percolation. The force of these statements
Conditions Modifying Duty of Water 201
will be more readily appreciated after a study of the results
given in the following table :
*Table showing the difference between the effectiveness of mulches developed from
different hinds of soil
/ — Loss of water per 100 days — -
Mulch Mulch Mulch Mulch
Black marsh soil : No mulch l-in. deep 2-in. deep 3-in. deep 4-in. deep
Tons per acre 588 355 270 256.4 252.5
Inches of water 5.193 3.12 2.384 2.265 2.23
Per cent saved by mulches 39.54 54.08 56.39 57.06
Sandy loam :
Tons per acre 741.5 373.7 339.3 287.5 315.4
Inches of water 6.548 3.3 2.996 2.539 2.785
Per cent saved by mulches 49.6 54.24 61.22 57.47
Virgin clay loam:
Tons per acre 2,414 1,260 979.7 889.2 883.9
Inches of water 21.31 11.13 8.652 7.852 7805
Per cent saved by mulches 47.76 59.38 63.13 63.34
The results in this table were secured by filling cylinders of
galvanized iron, having a depth of 22 inches and a cross-section
of -f5 of a square foot, with the soil named, by thorough tamp-
ing, and then removing a depth of these soils equal to 1, 2, 3
and 4 inches, returning enough of each kind in a loose, crumbled
condition to fill the cylinders again level full, thus forming
mulches of the respective depths. Under these conditions, the
soils were exposed in the open field during 42 days to the normal
atmospheric conditions, except that during times of rain the
cylinders were covered. Water was added every 10 days to the
reservoirs shown in Fig. 36, bringing the lowered surface back '
to a standard level.
It will be seen that while the black marsh soil lost water
through the unmulched surface at the rate of 5.88 tons per acre
per day, the sandy loam lost water at the rate of 7.42 tons,
and the virgin clay loam at the rate of 24.14 tons per acre per
day, the latter exceeding the two former more than three- and
four- fold. And, then, when the losses through mulches of cor-
responding depths are compared, it will be seen that although
♦Fifteenth Ann. Kept. Wis. Agr. Expt. Station, page 137.
202
Irrigation and Drainage
these are much less than through the undisturbed soil, yet the
relative differences are nearly as large. That is to say, the soil
•which, in the firm condition, has brought the largest amount of
water to the surface, has also, when its surface 1, 2, 3 or 4
Fig. 36. Method of measuriiig effectiveness of inulclies.
inches were converted into a mulch, permitted the largest losses
to take place ; while the soil having the slowest rate of loss
when the surface was firm has also given the least evaporation
through the several depths of mulches.
If the losses per 100 daj^s, expressed in inches, are brought
into contrast, they stand as shown below:
No mulch
1-ineh
mulch
2-inch
mulch
3-inch
mulch
4-inch
mulch
INCHES
INCHES
INCHES
INCHES
INCHES
21.31
11.13
3.12
8.01
8.65
2.38
6.27
7.85
2.27
5.58
7.81
5.19
2.23
Difference
16.12
5.58
It will be seen from this table that very wide differences
exist between the losses of moisture thi-ough mulches of like
Conditions Modifying Duty of Water 203
depth, when developed from soils of different textures, and it is
plain that with equal losses by percolation from the three soils
here under consideration, more water would be required to bring
a crop to maturity on the virgin clay loam than on either of the
other soils, and hence, that the duty of water would be less,
supposing, of course, that the three soils were equally fertile.
Where water is plentiful and is being used freely, and es-
pecially where irrigation by flooding is being practiced, the soils
having the coarsest, most open texture will waste the most water
by percolation through the zone of root feeding. Hence on this
account the duty of water would be smaller on these soils than
on those having finer texture. But, on the other hand, the sur-
face evaporation from the closer soils is so much greater than
from the sandy soils that the duty of water is much more nearly
equal on them than it could be were it not for these opposite
characteristics.
Bearing upon this point E. Perels,* citing Eduard Markus,
gives the results of observations covering three years in northern
Italy on different kinds of soils and with different crops, from
which it appears that rice, meadows and field crops use water in
the ratio of 7 to 3 to 1, respectively, and when field crops are
grown upon very heavy soil, heavy soil, medium soil, or light
soil, they take water in the ratio of —
Very heavy soil Heavy soil Medium soil Light soil
100 . . to . . 115 . . to . . 168 . . to . . 230
It is quite probable, however, that these ratios represent the
relations of the degree of permeability of these soils under the
conditions of the district, rather than the necessary amounts of
water reqiiired for irrigation on these soils, where simply the
transpiration from the crops and the evaporation from the soils
is considered. In the cases of the I'ice and meadows, it is cer-
tain that large percolation or surface drainage must have occurred.
The losses of water by seepage from canals and reservoirs
♦Landwirthschaftlicher Wasserbau, p. 501.
204 Irrigation and Drainage
and the various distributaries will, of course, be relatively greater
in regions of soils of coarse texture than where the soils are finer,
so that here is a factor modifying the duty of water as con-
sidered from the standpoint of the water company and irrigation
engineer especially, but also with the large irrigator, who has
extensive distributaries, through which the water must be con-
veyed before it is finally taken out upon the land. It should be
emphasized that our discussion has reference to the duty of water
after it has reached the field where it is used.
If it shall be found true that the continued growth of large
crops upon a piece of land, and the consequent more complete
evaporation of all water brought to the soil, thus curtailing the
drainage, tends to develop alkalies to an injurious extent, or
other prejudicial salts, so that flooding or leaching by irrigation
shall be found necessary in order to restore fertility, then here,
again, the character of the soil will modify the amount of water
required.
3. The character of the rainfall will necessarily modify in a
marked manner the amount of additional water which may be
used to advantage in the production of crops. It has already
been pointed out on page 103 that the difference in the character
of the rainfall in parts of California, Oregon and Washington, as
compared with that of western Kansas and Nebraska, may explain
why equivalent amounts of rain are much more effective in the
former than in the latter regions, and if it is true that the fre-
quent summer rains east of the Rocky Mountains do tend to hold
the development of the roots of crops closer to the surface, and
also to destroy the effectiveness of soil mulches, it is clear that
the duty of water in climates where most of the growing season
is an uninterrupted rainless period will be relatively higher than
where frequent but inefficient showers tend to reduce the effi-
ciency of mulches, and to hold the roots of crops closer to the
surface. It is, therefore, likely to be found true that more water
will be required for like results in western Texas, Oklahoma,
Kansas, Nebraska, and the Dakotas, and similar climates, than
will be required where the whole summer season is one con-
tinuous interval of no rain.
Conditions Modifying Duty of Water 205
In still more humid climates, but where there are frequent
recurrences of intervals of drought, the amount of water which
must be used in order to secure full yields will be relatively
larger than would be requii'ed in rainless countries, because the
surface losses of moisture will be relatively greater, as well as
those from percolation and drainage.
4. The character of the subsoil, as well as that of the surface
soil, is an important factor in determining the duty of water,
especially in the hands of the unskillful irrigator, and par-
ticularly so if he possesses no knowledge, or exercises poor
judgment, regarding the water-holding power of the soil to
which the water is being applied. Where the texture of the
subsoil is coarse and its water-holding power small, it requires
the best of judgment, both in regard to the amount of water
which may be applied at one time and as to the rate at which it
should be led over the surface or along the furrows, in order
that there shall be no waste by percolation below the depth of
root feeding.
It has been pointed out that even moderately fine sands 8
feet above the ground water quickly lose by percolation all but 4
per cent, or less, of their dry weight, of the water given to them.
Since plants will suffer for water when such soils have lost all
bijt 2 to 3 per cent of their dry weight of the soil moisture, it
follows that in 4 feet in depth of such a subsoil there is room for
only 1.5 to 2 per cent of water, or 1 to 1.5 inches, to be applied
at one time, without loss taking place by percolation below the
depth of root action. It is plain, therefore, that on open soils
the duty of water will be relatively small, unless great skill and
rare judgment are exercised in its application.
5. The frequency and thoroughness of cultivation after irriga-
tion is another factor which will modify the duty of water. For
the effectiveness of soil mulches is modified as well by the fre-
quency of stirring as by its depth. The force of this statement
will be better appreciated when the results given in the table
which follows have been considered:
724.1
551.2
545
527.8
6.394
4.867
4.812
4.662
23.88
24.73
27.1
724.1
609.2
552.1
915.4
6.394
5.38
4.875
4.552
15.88
23.76
28.81
724.1
612
531.5
495
6.394
5.28
4.694
4.371
15.49
26.6
31.64
206 Irrigation and Drainage
Table shoivinj the loss of toater from a virgin clay loam through mulches 1, Z,
and 3 inches deep, when cultivated once in two weeks, once per week, and
tioice per iveek
Not Once in Once per Twice per
cultivated 2 weeks week week
Cnltivated 1 inch deep— per acre per acre per acre per acre
The loss in tons per 100 days was
The loss in inches per 100 days was. .
The percentage of water saved was. .
Cnltivated 2 inches deep—
The loss in tons per 100 days was
The loss in inches per 100 days was. .
The percentage of water saved was . .
Cnltivated 3 inches deep—
The loss in tons per 100 days was
The loss in inches per 100 days was. .
The percentage of water saved was. .
It will be seen from this table that with each of the three
depths of cultivation the loss of water decreased with the fre-
quency, so that the per cent of moisture saved by the cultivation,
when computed on that which was lost with no cultivation, was
more than 31 for 3 inches deep twice per week, as against a sav-
ing of only 15 per cent where the same cultivation was made only
once in two weeKs. That is to say, if one is cultivating ground
of this character 3 inches deep twice per week, the saving over
no cultivation may be at the rate of 2.29 tons per acre per day,
or 22.9 tons per each 10 days, or 2 acre-inches per 100 days.
The results presented in the table were obtained in our
plant-house, with cylinders 52 inches deep and 18 inches in
diameter, filled with soil under a nearly still air and a compara-
tively low mean temperature, not exceeding 55° P., during the
short days and long nights of December and January, so that
the observed losses in the several cases must be looked upon as
small, and below what may obtain under field conditions. It is
plain, therefore, that in orchard irrigation and in arid climates,
under a clear sky, dry air and high temperature, the duty of
water during the long seasons may be very materially increased
by adequate cultivation, and decreased by the lack of it.
The same will also be true, but in a less marked degree,
Conditions Modifying Duty of Water 207
with all cultivated crops where the soil is not completely shaded
by the plants on the ground.
6. Tlie closeness of planthtg is another factor which affects
the duty of water when this is expressed iu terms of land served,
rather than in terms of crop produced. This is particularly true
in climates where a rainy season contributes a considerable por-
tion of the moisture needed to produce a crop ; because if one is
contented with a small yield per acre, a comparatively thin stand
upon the ground, with thorough tillage, may often be brought to
full maturity with a relatively small amount of water applied
by irrigation, thus making the duty of water to appear very high,
whereas if the plants were made to stand as closely as the sun-
shine would permit, much more water, when expressed simply
in acre-inches, would be required. The real duty, however, might
be even higher in the second ease, when expressed in terms of
yield, per acre.
7. The fertility of the land is still another factor which
affects the duty of water, tending to make it appear less the
richer and more fertile the soil is, when the standard of com-
parison is the unit area rather than the yield of crop. This
apparent decrease in the duty results from the larger evaporation
of water which takes place from the more vigorous growth of
vegetation, and the closer stand which the larger amount of
available plant-food renders possible. In such cases as these,
however, the real duty of water is higher on the most fertile soil,
when this is based upon the actual yields per acre ; not so much
because the plant uses the water more economically, as that the
necessary loss from the soil itself is relatively less with the large
yield than it is with the small yield per acre. The loss from the
soil direct may even be actually larger with the smaller crop on
the ground, on account of a less complete shading and stronger
air movement close to the surface.
8. The frequency of applying loater also modifies the quantity
which will be used during a season. This may be true even
when the greatest skill is exercised in the application of the water.
In the first place, too frequent application of water in small
quantities at a time not only increases in a marked degree the
208 Irrigation and Drainage
direct loss of moisture from the wet, unmulehed soil ; but it may
have a tendency, as has been pointed out, to induce a superficial
development of roots, causing the crop to show signs of need of
water sooner than would be the case if a smaller number of more
thorough irrigations were resorted to. This is so, not only be-
cause the water disappears sooner from the soil, but also because
of the larger amount of root-pruning which results from culti-
vation where the roots are developed near the surface of the
ground.
It is probable that a large supply of water in the soil during
the early stages of growth of many plants tends to develop in
them a possibility for using more water. In some, at least, of
our experiments with corn, oats, potatoes and clover, where we
have started with like amounts of water in the soil, and have
watered one set of plants every seven days while the others
were allowed to go without water until the soil was so far ex-
hausted that the plants were plainly suffering for want of mois-
ture, it was found that these plants not only did not use water as
rapidly after they were given it as did those which had been
watered every week, but they used the water they did have with
relatively greater economy. Whether this was because the plants
were smaller, and thus presented a smaller surface to the air and
sun, or whether the size or number of breathing pores per unit
area of foliage was actually less, cannot yet be stated ; but it
appeared evident that for some reason the plants which had not
been watered at first were later not able to use the larger amount
of water which was given to them, as they might have done had
they been more freely watered at first.
THE AHIOUNT OP WATER USED IN IRRIGATION
It is very difficult, indeed, to get data bearing
upon this important subject which may be regarded as
in every way satisfactory and trustworthy. Nearly all
statistics are necessarily so general in their character,
the exact amount of land to which the water of a
Amount of Water Used in Irrigation 209
stated canal is actually applied is so uncertain, and
the amount of water lost by seepage and evaporation
from the canal and its distributaries before the laud to
which it is nominally applied is reached, is so variable
and indeterminate that the best which can be said
regarding most available data is that they should be
looked upon as only rough approximations. Further
than this, it must be constantly borne in mind, when
dealing with the problem of how much water is re-
quired for irrigation, with all the variations of weather,
climate, crops, soils and degrees of skill in applying
water which exist, that were sufficiently exact data at
hand covering a wide range of conditions, it would
still be impossible to combine them into averages not
requiring wide marginal allowances to be made when
specific application is desired. But, notwithstaudiug
all this, general statements may be helpful if only
they are rightly considered.
Referring, fii'st, to Italy,* where u-rigation has long
been systematically practiced, it is generally calculated
that in Piedmont one cubic foot of water per second
will serve satisfactorily 55 acres of land ; but on ac-
count of loss hy evaporation and seepage, this is
reduced to 51.4 acres, this providing sufficient for
4.63 inches of water every 10 days during the irri-
gation season.
Under the canal of Ivrea, where a large amount
of rice is grown, which is given more water than ordi-
nary crops, one second -foot serves but 42.75 acres, or
at the rate of 5.668 inches every 10 days ; and under
*Baird Smith, Italian Irrigation, Vol. I,
N
210 Irrigation and Drainage
the Gattinara canal, water is provided which may be
applied at the rate of 5.289 inches per 10 days. But
u r the Busca canal, where the utmost economy is
pr ced and every drop is saved, the duty of water
is so much increased that one second -foot serves 106
acres, making a depth of water equal to 2.245 inches
every 10 days for the irrigation season.
Bringing all cases cited by Smith into one table,
and expressing the second -foot in inches of water per
10 days, the following results are found :
Amount of water used for irrigation in Italy
No. of acres
per sec. foot
No. of inches of water
per 10 days
No. of acres
per see. foot
No. of inches of water
per 10 days
51.4
4.63
99.3
2.397
45
5.289
80.4
2.96
106
2.245
66.62
3.572
100.6
2.366
61.8
3.851
63
3.778
66.6
3.574
90.6
2.627
69.2
3.44
50.3
4.732
63.9
2.837
70
3.4
67.2
3.542
77
3.091
90.4
2.633
69
3.449
This gives a general average for ordinary crops of
3.39 inches of water every 10 days and 33.9 inches
per 100 days, were it used at such a rate for so long
a period.
In the rice irrigation of Italy, the amount of water
provided is said to be at the rate of 5.568 inches,
5.921, 3.412, 9.521, and 3.334 inches every 10 days
in as many districts, or an average of 5.55 inches per
10 days.
Amount of Water Used in Irrigation 211
In Spain, where the rainfall is less than in Italy,
and where greater economy of water is practiced, 19
important allotments* of water give an average ot
2.353 inches every 10 days for various sections ot
that country.
In France, in the Department of the Upper
Garonne, contracts were made calling for water at
the rate of three -fourths of a liter per hectare per
second, which makes a duty of about 93.25 acres per
second foot, or water applied at the rate of 2.552
inches every 10 days. In the department of Vau-
cluse, the concession was at the rate of only 1.361
inches per 10 days.
In Egypt, Willcockst states that in winter water
is applied at an average depth of 10 c. m., equal to
3.937 inches, once in 40 days, which is a rate of
,984 inches once in 10 days; but in summer the first
watering is at the rate of 11.5 c. m., equal to 4.528
inches, while subsequent waterings are at the rate of
3.412 inches in depth. Cotton requires this amount
once in 20 days, or at the rate of 1,706 inches per 10
days. Rice is given water at the rate of 3.412 inches
once every 10 days, and maize gets the same amount
every 15 days, or at the rate of 2.276 inches in depth
every 10 days.
Wilson! gives a table of general averages of the
duty of water in different parts of the world, which
we put in the form stated below:
*Hall, Irrigation Development, p. 523.
tWillcopks, Egyptain Irrigation, pp. 234, 235.
tMannal of Irrigation Engineering, Sec. Ed., p. 49.
212
Irrigation and Drainage
Amount of water used in irrigation in
Name of country No. of acres per sec. -ft.
Northern India ... 60 to 150
Italy 65 to 70
Colorado 80 to 120
Utah 60 to 120
Montana 80 to 100
Wyoming 70 to 90
Idaho 60 to 80
New Mexico 60 to 80
Southern Arizona . . 100 to 150
San Joaquin Valley . 100 to 150
Southern California . 150 to 300
different countries
No. of inches per 10 days
3.967 to 1.587
3.661 to 3.4
2.975 to 1.983
3.967 to 1.983
2.975 to 2.38
3.4 to 2.644
3.967 to 2.975
3.967 to 2.975
2.38 to 1.587
2.38 to 1.587
1.587 to .793
E. Perels* tabulates the duty of water in Algeria
as follows :
Water required for irrigation in Algeria
No. of
waterings
„y_ ^__ J
Crops
Each
application
During the
season
Length of
culture period
INCHES IN
INCHE.S IN
MONTHS
DEPTH
DEPTH
Alfalfa . . .
10
1.575
15.75
6
Vegetables .
. 36
1.575
56.7
6
Cotton . . .
)
Flax ....
10
2.52
25.2
5
Sesame . . .
s
Maize ....
4
1.575
6.3
2
Winter grain
3
3.937
11.87
7
Oranges . . .
. 12
1.575
18.9
6
Tobacco. . .
4
1.575
6.3
3
Grapes . . .
4
4.725
18.9
3
From another general table giving the duty of
water in different countries, by Flynn.t the results
which follow are derived:
♦LandwirthsehaftUeher Wasserbau, zweite Auflage, p. 502.
t Irrigation Canals and Hydraulic Engineering, p. 293.
Amount of Water Used in Irriyation 213
Amount of water nsed in irrigation in different countries
Name of 1
Locality country p
Eastern Jumna Canal India
Western Jumna Canal .... "
Ganges Canal "
Canals of Upper India "
Canals of India — average ... "
Bari Doab Canals "
Madras Canals (rice) "
Tanjore (rice) "
Swat Eiver Canal, 1888-89 . . . "
Swat Eiver Canal, 1889-90 . . . "
Western Jumna Canal, 1888-89 . ' '
Western Jumna Canal, 1889-90 . ' '
Bari Doab Canal, 1888-89 ... "
Bari Doab Canal, 1889-90 ... "
Sirhind Canal, 1888-89 . ... "
Sirhind Canal, 1889-90 .... "
Chenab Canal, 1888-89 ....
Chenab Canal, 1889-90 "
Nira Canal "
Genii Canal Spain
Juear (rice) "
Henares Canal "
Canals of Valencia "
Forez Canal France
Canals south of France .... "
Sefi Canals, Southern France . "
Sefi, or Lower Nile Canals . . Egypt
Sefi, or Lower Nile Canals . . "
Canals of Northern Peru .... Peru
Canals of Northern Chili .... Chili
Canals, Lombardy Italy
Canals, Piedmont "
Marcite "
Sefi Canals, Victoria Australia
1. of acres
• sec. -foot
No. of inches
per 10 days
306
.778
240
.989
232
1.026
267
.891
250
.952
155
1.536
66
3.606
40
5.964
216
1.:J45
177
1.202
143
1.664
179
1.33
201
1.184
227
1.049
180
1.322
180
1.322
"154
1.545
154
1.545
186
1.28
240
.992
35
6.8
157
1.516
242
.984
140
1.7
70
3.4
60
3.877
350
.68
274
.867
160
1.488
190
1.253
90
2.644
60
3.877
1 to IS
238 to 13.22
200
1.19
214 Irrigation and Drainage
Amount of toater used in irrigation— continued
Name of No. of acres No. of inches
Locality country per sec. foot per 10 days
Sweetwater, San Diego .... California 500 .476
Pomona, San Bernardino ... " 500 .476
Ontario " 500 .476
California " 80tol50 2.975tol.587
Canals of Utah Territory . . . Utah 100 2.38
Canals of Colorado Colorado 100 2.38
Canals of Cache la Poudre ... " 193 1.233
Canals of Colorado " 55 4.328
It is apparent, from the data which have been
presented, that the amount of water actually used in
irrigation in different countries and for different crops
is an extremel}^ variable quantity; so much so, indeed,
that it is hardly possible to deduce from available sta-
tistics a mean value for the duty of water. But, using
the 100 cases at hand from all parts of the world, and
excluding those which apply to rice cultui'e and the
irrigation of water-meadows and sugar cane, it ap-
pears that a cubic foot of water per second is made
to serve on the average 117.6 acres. If this water
were applied to the land once in 10 days, it would
cover the surface to a depth of 2.024 inches each
watering, and during a season of 100 days would be
the equivalent of 20.24 inches of rain.
Sugar cane is a crop which demands large and fre-
quent irrigations in order to secure the largest returns
from the soil. In the Sandwich Islands one cubic
foot of water per second is required for 41.6 acres of
cane, and it is found that if the duty is made larger
than 60 acres per second -foot, a falling off in yield is
Highest Probable Duty of Water
215
sure to result. In India and Siam writers on this sub-
ject state that from 43 to 45 acres is the usual duty
of a second -foot. The mean value for good, thorough
watering appears to be 43.2 acres per second -foot, or
a depth of water aggregating, for the year, between 19
and 20 feet on the level.
If reference is again made to the table on page
198, it will be seen that this duty of water is much
smaller than was realized in the experiments cited.
According to the results there given, one second -foot
should be able to serve the number of acres stated in
the table below:
The highest probable duty of water for different crops expressed in acres per
second-foot for different yields per acre
Yield per
Wheat
Barley
Oats
Maize
Potatoes
Clover hay
acre
AORES
ACRES
ACRES
ACRES
ACRES
ACRES
15 bushels
529.2
593.0
1002
1039
20 "
352.8
395.3
751.5
779.2
30 "
264.6
296.5
501.0
519.5
40 "
176.4
197.6
375.7
389.6
50 "
141.1
158.1
300.6
311.7
60 "
117.6
131.7
250.5
259.7
2493.7
70 "
112.9
214.3
222.6
2137.4
80 "
98.8
187.9
194.8
1870.2
90 "
167.0
173.2
1662.4
100 "
150.3
155.8
1496.2
200 "
748.1
300 "
498.7
400 "
374.0
1 tOQ
322.7
2 tons
161.3
3 "
107.6
4 i«
80.7
216
Irrigation and Drainage
In constructing this table, the season of growth
has been taken at 100 days for wheat and oats, 80
days for barley, 110 days for maize, 130 days for pota-
toes, and 60 days for one crop of clover hay. It has
fui'ther been assumed that the ground at seeding time
is well supplied with moisture, while at harvest it is
only so much dried out as to have just become ready
for another watering.
As in the experiments which gave the fundamental
data for the table above, the soil was more closely
planted than is practicable under field conditions, the
loss of water by evaporation from the soil of the field
is likely to be greater, relatively, than was the case in
the experiments ; hence, the observed duty of water is
likely to be lower than the table indicates. Again,
in the case of the smaller yields per acre, the evapo-
ration from the soil will necessarily be relatively larger
than where the heavier crops are produced ; hence, the
duty expressed for water when the yields are small is
likely to be farther from the possibilities than in the
eases where the yields per acre are larger.
If the amount of water which the last table indi-
cates is required to produce a crop of the various
kinds is expressed in cubic feet, the figures will
stand :
8,640,000 eu. ft. of water may produce 7,056 bushels of wheat
8,640,000 " " " "
15,030
((
" oats
6,912,000 " " " " " '
7,906
(t
" barley
9,5040,000 " " " "
15,580
"
" maize
11,232.0000 " " " "
149,620
1 <
" potatoes
5,184,000 " " " "
322.7
tons of hay.
Duty of Water in Rice Culture 217
where the number of cubic feet is the product of one
second -foot into the number of seconds in the season
of growth, and the number of bushels is the product
of the yield per acre into the number of acres irri-
gated.
THE DUTY OF WATER IN RICE CULTURE
The aquatic nature of the rice plant makes the
demands for water quite different from those of ordi-
nary agricultural crops, and so different are these
needs that the quantity of water required to bring a
crop to maturity is determined by quite different
factors. The duty of water, therefore, in rice culture
could not consistently be considered in connection with
that of ordinary crops.
The normal habitat of this plant is low, swampy
lands, where the surface is more or less continuously
under water, and where such lands are available under
suitable conditions for rice culture, they are largelj'
brought into requisition for this purpose ; but the
seeding of the ground and the harvesting of the crop
make it needful that the fields shall be drained! at
times and at others flooded. Under these conditions,
there can be but little waste from seepage, and the
chief demands for water are created by the loss from
evaporation from the surface of the water, from the
growing crop, and from the wet soil when the fields
have been drained, together with the amounts which
are required for reflooding the fields after they have
been drained. Occasionally threatened attacks upon
218 Irrigation and Drainage
the crop by insect enemies make an extra flooding or
drainage necessary, and this increases the demand for
water. Further than this, in order that the crop may
be the best, the water must not remain long stagnant,
and this requires either alternate flooding and drain-
ing, or else a considerable steady surplus flow of water
over the fields.
In order to secure more economical methods of
seeding and harvesting the rice fields, this crop is
extensively grown on naturally dry lands, which may
be readily checked off into flooding basins, to which
the water may be admitted and withdrawn at pleasure.
In these cases, there is added to the demands for
water already mentioned the loss from seepage. This
loss from seepage may be so large that rice irrigation
cannot be economically practiced on uplands unless
they are quite flue and close in texture, so that the
rate of seepage will be small, or unless the normal
level of the ground -water is within a few feet of the
surface. Even here the subsoil must be pretty close,
or the loss of water by under- drainage will be too
large.
The various available sources of data regarding the
duty of water in rice irrigation place the amounts of
water used as varying all the way from one second -foot
for 25, 28, 30, 35, 40, 55 and 66 acres of rice, thus
making an average of 38.6 acres per cubic foot of
water per second, and this is equivalent to covering
the surface with water about 6.2 inches deep every 10
days.
Duty of Water on Water-meadows 219
THE DUTY OP WATER ON WATER-MEADOWS
In this form of irrigation, immense volumes of water are
used on the land. In Italy, where the practice has attained
the highest stage of perfection, where it may have had its
origin, and from which been introduced into France, and even
into England at the time of the Eoman invasion, the duty of
water appears to average only about 1.5 acres per cubic foot per
second. On these meadows in Italy there is maintained a nearly
continuous flow of water, night and day, from September 8 to
March 28 of each year, this being the legal time allotted to
Marcite, or winter-meadow irrigation.
The lands are so laid out that the roots of the grass over the
whole meadow are continuously submerged beneath a thin veil
of relatively warm running water, this being turned off only long
enough to cut the grass, which is done two or three times during
the winter season, the green grass being used for the winter feed
of dairy cows, which are largely kept in the irrigated portions of
Italy. So large is the quantity of water used during a single
season on these meadows that did none of it drain away they
would become submerged to a depth of 300 feet.
Carpenter, quoting Mangon, states that in southern France
and in the Vosges, where the most careful measurements of the
water applied to the meadows have been made, amounts are used
in some cases suflEieient to cover the surface 1,400 feet deep ;
and that of this great volume, as much water as 160 feet on the
level sinks into and percolates through the soil of the field during
a winter season. But even in the summer irrigation, as much as
374 feet of water on the level are applied between April and
July, while of this amount no less than 88 feet percolates into
the ground or is evaporated.
The meadows upon which these large volumes of water are
applied are usually permanent ones, and have had their surfaces
fitted with the greatest care, so that the relatively warm water
may be kept steadily flowing over the surface about the roots of
the grass in a thin veil until it is ready to cut, when it is turned
off only long enough to remove the crop.
220 Irrigation and Drainage
In Italy these heavy and continuous irrigations stimulate
the grass to grow the year round, and in the vicinity of Milan,
where the irrigation canals are led through and beneath the
city, relieving it of all its sewage, this warm and highly ferti-
lizing water so stimulates the growth of grass that seven heavy
crops are taken from the ground each year, aggregating, accord-
ing to Baird Smith, 45 to 50 tons per acre, and in exceptional
cases one-half more than this.
It will be readily understood that the application of water
to these winter and summer water-meadows in such large vol-
umes has quite a distinct purpose from that of supplying the
needed moisture for the transpiration of the grasses. In short,
the practice has been found to be a sure way of greatly pro-
longing the growing season of each year, and a cheap means of
permanently maintaining a high state of fertility of the soil.
THE DUTY OF WATER IN CRANBERRY CULTURE
In the irrigation of cranberries, as in the case of rice and
water-meadows, the purpose of the treatment is quite distinct
from that of ordinary irrigation. It is true that this crop
demands a large amount of water, but its normal habitat is such
that ordinarily it is abundantly supplied by natural sub-irri-
gation. In this case, the water is demanded chiefly to protect
the crop against the ravages of insects and injury from frost,
and to prevent winter-killing.
As the surface of the ground -water is seldom more than one
to two feet below the surface of the bog, and as the peat and
muck above the water are at all times nearly saturated, the
amount of water required for cranberry irrigation is but little
more than that necessary to submerge the vines, which will
rarely be more than .8 to 1.5 acre-feet. But, except for the
flooding for winter protection, the demands for water are so
peremptory and the time so short which can be allowed for sup-
plying it, that but a low duty is possible when this is measured
by the rate at which the water must be delivered.
Duty of Water in Cranberry Culture 221
When it is protection against frost which is required, the
marsh must be given as much as 4 to 6 inches of water on the
level in nearly as many hours. To do this will require a stream
of 1 to 1.3 cubic feet per second per acre. But when the flood-
ing is to destroy insects, the haste need not be so great ; while
for winter flooding, a relatively small stream will answer the
needs, as six weeks, if need be, may be taken in the flooding,
and as the ground -water surface around the marsh is usually
above the marsh itself, the loss from seepage is small, as must
also be that by evaporation during the winter.
CHAPTER VI
FREQUENCY, AMOUNT AND MEASUREMENT OF WATER
FOR SINGLE IRRIGATIONS
To have become able to apply water to crops at
the right time, in the right amounts and in the best
manner is to have attained the acme of the art of
irrigation. Unfortunately, it is no more possible to
bear a man to this position on the vehicle of language
than it is a cook to the art of making the best bread.
Both arts are founded upon the most rigid of laws,
which may be readily and certainly followed when the
conditions have been learned. But the minutiae of
essential details are so extreme that words fail utterly
to convey them to the mind, and they must be per-
ceived through the senses, to be grasped with such
clearness as to lead unerringly to the right results.
There are, however, general principles underlying the
art, which may be readily stated, and, when com-
prehended, place one in position to more quickly grasp
the details essential to complete success in the appli-
cation of water to crops.
THE AMOUNT OF WATER FOR SINGLE IRRIGATIONS
In humid climates, there is always more or less
soil -leaching, resulting from super -saturation of the
(222)
Amount of Water for Single Irrigations 223
soil during times of heavy or protracted rains. This
leaching is usually looked upon as a necessary evil,
which results in a waste of fertility. Whether this
conviction is well founded, or whether a certain
amount of soil washing is indispensable to unim-
paired fertility, it appears to the writer is one of
the important soil problems awaiting positive demon-
stration. The accumulation of alkalies in the soils
of arid climates, where relatively small leaching is
associated with large evaporation, and the tendency
of alkalies to become intensified where irrigation has
been long practiced, are facts which suggest that
there may be such a thing as too great economy of
water in irrigation.
But, waiving this possibility of demand for water,
and all of those cases where the water is applied [for
other purposes than meeting the ordinary needs of
vegetation, the fundamental conditions which deter-
mine the amount of water which should be applied at
a single irrigation are : (1) the capacity of the soil
and subsoil to store capillary water; (2) the depth
of the soil stratum penetrated by the roots of the
particular crop ; (3) the rate at which the soil below
the root zone may supply water by upward capillarity
to the roots ; and (4) the extent to which the soil
and subsoil have become dried out.
On the other hand, the conditions which determine
the frequency of irrigation are : (1) the amount of
available moisture which may be stored in the soil ;
(2) the rate at which this moisture is lost through
the crop and through the soil ; and (3) the degree
224 Irrigation and Drainage
of desiecatiou of the soil which the particular crop
will tolerate before serious iuterfereuce to growth re-
sults.
THE CAPACITY OF SOILS TO STORE WATER
UNDER FIELD CONDITIONS
The amount of water which may be stored in soils under
field conditions varies between wide limits with the character
and texture of the soils, and also with the distance of standing
water in the ground below the surface.
When a fine sand will hold in the first foot above the
ground- water 23.86 per cent of its dry weight of water, at 4 feet
above it was found to hold only 8.12 per cent, and 8 feet above
only 3.14 per cent of the dry weight. When these amounts are
expressed in pounds per cubic foot, they stand only a little more
than 23.86 pounds, 8.12 pounds, and 3.14 pounds, a cubic foot
of the dry sand weighing about 105 pounds.
In the case of a natural field soil of sandy clay loam with
clay subsoil changing to a sand at 4 feet, and where the
ground-water changed during the season from 7.6 feet below
the surface to 8.4 feet, the water content of the soil was found
to be as follows:
1st ft. 2d ft. 3d ft. 4th ft. 5th ft. 6th ft. 7th ft.
lbs. lbs. lbs. lbs. lbs. lbs. lbs.
■water water water water water water water
July 25 10.44 16.91 14.81 10.38 7.82 13.66 22.29
October 2 9.49 16.27 14.41 6 99 7.74 7.85 19.35
Loss .95 .64 .4 3.39 .08 5.81 2.94
During this interval there had been a rainfall of 10.84
pounds per square foot. There is no doubt that in the upper
4 feet a considerable part of the water was lost through surface
evaporation. It is quite likely, also, that a portion of the loss
sho\%Ti in the 5th, 6th, and 7th feet was due to an upward capil-
lary movement. But there is little reason to doubt that the
Amount of Water for Single Irrigations 225
chief loss shown in the lower three feet is due to downward
drainage or percolation, owing to a lowering of the ground-
water surface.
The 8-foot column of fine sand, referred to above, lost water
by percolation in 22 hours and 46 minutes, after full saturation,
equal to 6.35 per cent of the dry weight of the whole column ;
and as this must have come almost wholly from the upper 4
feet, the water there must have been reduced in that time more
than 12 per cent, which would leave a saturation of only 8
per cent.
But as plants would suffer severely for water in a soil of
this texture when the moisture was brought down to 4 per cent,
it is plain that only from 2 to 4 per cent of the weight of such
a soil can be added at one irrigation without entailing severe
loss by percolation below the depth of root-feeding. Taking a
cubic foot of such a soil at 105 pounds, the maximum irrigation
which could be applied without severe loss, supposing the ground
to be wet down 5 feet and the soil to have dried 3 per cent,
would be 15.75 pounds per square foot, or 2.86 inches in depth.
The sand in question, however, is more open than most agri-
cultural soils; hence it follows that more than 2 inches of water
may be safely applied at one irrigation to any crop much in
need of water.
By taking samples of soil in a field of maize and clover
when the corn leaves were badly curled and when clover wilted
quite early in the forenoon, the following moisture conditions
were found :
Soil moisture relations when groioth is brought to a standstill
Depth of sample Clover
PER CENT
0-6 iu. clay loam 8.39
6-12 8.48
12-18 " reddish cl.iy 12.42
18-24 " " " 13.27
24-30 " sandy clay 13.52
40-43 " sand 9.53
Maize
Fallow ground
ER CENT
PER CENT
6 97
16.28
7.8
17.74
11.6
19.88
11.98
19.84
10.84
18.56
4.17
15.9
226 Irrigation and Drainage
The moisture contained in the fallow ground, determined at
the same time, shows how much water such a soil may hold
against a drought and against percolation below root action.
The amount of moisture, too, in this fallow ground happens
to stand just at the under limit for most vigorous plant-growth
in this type of soil, while the upper limit is given in the table
below for comparison :
Hhoiuing upper and lower limits of best amount of soil moisture for one type of soil
Kind and depth Lower limit of Upper limit of Available
of soil soil moisture soil moisture soil moisture
PEU CENT PER CENT LBS. PER CU. FT.
Clay loam, first foot 17.01 25 77 6.92
Reddish day, second foot 19.86 24.3 4.112
Sandy clay, third foot 18.56 24.03 5.722
Saud, fourth foot 15.9 22.29 6.786
Total 23 55
It will be seen from this table that to bring the surface four
feet of soil from the lower limit of the best productive stage of
water content to the upper limit requires an application of 23.55
pounds per square foot, or a depth of irrigation equal to 4.527
inches.
It is quite certain that with a greater distance to standing
water in the ground, the 4th foot, and probably also the 3d foot,
could not have retained the amount of water shown by the table ;
and, hence, that an irrigation of 4.5 inches on such a soil would
have resulted in some loss by percolation below the depth of
root feeding.
If it should happen that a soil like the one in question be-
came as dry as is shown in the table on page 225, then the depth
of irrigation required to bring the moisture content up to the
upper limit of productiveness would be for the maize 11.37 inches,
and for the clover 9.39 inches, supposing the ground-water to be
at the time not more than 7 feet below the surface.
It follows, therefore, from the observations and data pre-
sented, that the amount of water required for one irrigation,
where the soil has not been permitted to become too dry, and
JDexith of Boot Penetration 227
where the aim is to bring the soil moisture to the upper limit
of productiveness without causing percolation below 4 or 5 feet,
will range from about 2.5 inches on the most open soils to 4.5
inches on soils of average texture. But when excessive drying
of the soil has taken place, then the amount of water applied
may range from 3.75 inches on the most open soils to as high as
even 11 inches on that which is of medium or fine texture. It
should be understood that many soils, when they become very
dry, develop shrinkage cracks, which permit very rapid and ab-
normally large percolation if excessive amounts of water are
applied at one time, and this without saturating the soil, the
water simply draining through the large open channels. In such
cases repeated smaller applications of water will ensure less loss
by percolation, permitting the soil to expand and close up the
shrinkage cracks.
THE DEPTH OF ROOT PENETRATION
The greater the depth to which the roots of a
crop may feed to advantage in the soil, the larger
may be the amount of water applied to the field at a
single irrigation without any passing beyond the zone
of root action, simply because 2 feet of soil will store
more water than 1 foot, and 10 feet more than 5. But,
further than this, where the roots of a plant penetrate
the soil deeply and spread widely, a miich smaller per
cent of water in the soil will enable the plant to ob-
tain enough to carry On its functions to good advan-
tage. This is so because the roots go to the moisture,
and do not, therefore, need to wait for the moisture to
come to them at the extremely slow rate it is known
to travel in a relatively dry soil. Then, too, when a crop,
by reason of its great spread of root, is able to meet
228
Irrigation and Drainage
Fig. 37. Penetration of roots of prime on peach in arid soil of
California. (Hilgard.)
Depth of Root Penetration
229
its needs in a dryer soil, it is evident that a much
higher duty of water is possible, for the simple reason
that none can be lost by percolation, and much less
will be lost by surface evaporation, even with deficient
tillage.
We have already called attention to the probable
deeper rooting of plants in soils of arid regions, where
Fig. 38. Penetration of apple root iu Wisconsin, 7 years planted.
Depth 9 feet. (Ooff.)
there is less distinction between the soil and subsoil,
than in those of humid climates. Since writing that
section, we have received Professors Hilgard and
Loughridge's Bulletin 121, in which they emphasize
this point by placing iu evidence a photo -engraving
of a prune tree on a peach root exposed in the soil
to a depth of 8 feet, and represented in Fig. 37. The
method they have used in exposing the root appears,
230
Irrigation and Drainage
from the photograph, to have destroyed nearly all but
the main trunks, unless it was true that the active
Fig. 39. Penetration of grape roots in Wiseou
Depth 6 feet. (Goflf.)
absorbing surfaces were chiefly still more deeply buried
in the soil than the excavation extended. This appears
quite likely to have been the case, for this penetra-
Depth of Root Penetration
231
tion is no greater than has been found in soils in
Wisconsin.
Fig. 40. Penetration of rasplierry roots in Wisconsin soil.
Depth 5 feet. (Goff.)
Professor Goff has washed out the roots of the
apple, grape, raspberry and strawberry, showing the
extent of their development in a loamy clay soil
232
Irrigation and Drainage
underlaid by a reddish clay subsoil, which changed
through a sandy clay into a mixed sand and gravel,
at 4 or more feet. His photographs, reproduced in
Figs. 38, 39, 40 and 41, show to what extent the roots
of these fruits penetrate the soils and subsoils of
Fig. 41. I\-iieli'ali..ii .ii' rM,,tx ,,i >tia\s i.i-iry in iii:iti.Mi riA\> iu Wi.scuiiiiu
soil. Depth 22 inches. (Goff.)
Wisconsin, where the annual rainfall ranges from 28
to 40 inches. It will be seen from the legends that
the roots of the apple have extended to a depth of
fully 9 feet, the grape more than 6, and the raspberry
more than 5. It is plain, therefore, that even in the
soils of humid climates the roots penetrate so deeply
that the moisture of the surface 8 to 10 or 12 feet is
Depth of Root Penetration
233
laid under tribute by them, and
this makes it clear that the stor-
age room for water in the soil for
many of the fruits may be much
greater than we have pointed out
above.
In the case of the strawberry,
however, the figure shows that it
is a particularly shallow feeder,
and, therefore, is certain to suffer
severely in dry times if not irri-
gated.
In Fig. 42 are shown the roots
of alfalfa only 174 days from
seeding. These had forged their
way through so close a clay subsoil
that more than four days of con-
tinuous washing were required to
dissolve away a cylinder of soil 1
foot in diameter and 4 feet long.
The roots, however, had penetrated
this soil to a depth exceeding four
feet, and the nitrogen-fixing tuber-
cles were already developed 22
inches below the surface.
In the rigid data here pre-
sented, combined with that shown
in Figs. 10 and 11, we have a
I'ational basis upon which to build
a practice of irrigation, so far as
that relates t(? the depth of soil
Fig. 42. Roots of
in Wisconsin 17
from seeding.
234 Irrigation and Drainage
which may be moistened and yet be within the reach
of plants.
THE FREQUENCY OF IRRIGATION
The data presented in the last two sections are a
portion of those required to understand the rationale
of this important subject. Viewed from the standpoint
of labor involved in distributing water for irrigation,
it is evident that the fewer the number of irrigations
the smaller maj^ be the labor involved and the lower
the cost. Moreover, the less often the surface of the
soil is wet, the smaller will be the loss of water by
evaporation and by seepage in bringing the water
to the fields ; hence, the higher will be the duty of
water.
The most general rule which can be laid down
governing the frequency of irrigations and the amount
of water to be applied at one time, is to apply as much
water to the soil which is available to the crop as the
crop will tolerate without suffering in yield or quality,
and then husband this water with the most thorough
tillage practicable, in order to reduce the number of
irrigations to the minimum.
It has been shown that a crop of maize yielding
70 bushels per acre may be brought to maturity in 110
days with 11.75 acre-inches of water. It has also been
shown that a soil of medium texture may carry in the
surface 4 feet 4.5 inches of available water, or, if ex-
tremely open, 2.5 inches. Could so high a duty of
water as this be attained under field conditions, three
Frequency of Irrigation 235
irrigations would be required for such a crop of maize
on the medium soil and five on the most open one,
making the intervals between waterings 37 and 22 days;
but if the yield was 100 bushels per acre instead of
70, the number of irrigations required would be four
or seven, and the intervals between waterings would be
27 days for the medium soil and 15 days for the most
open one.
Computing for wheat on a similar basis, with a
yield of 40 bushels per acre, requiring 12 acre -inches
of water under the conditions of the highest duty, the
number of irrigations would have to be three or five,
at intervals of 33 or 20 days, according as the texture
of the soil was medium or very coarse; while a crop
of barley yielding 60 bushels per acre in a period of
88 days would need 12.84 acre -inches, to be applied in
three or five irrigations, at intervals of 29 or 18 days.
These three cases may be taken as types of the
highest limits likely to be attained under the best of
field conditions, and they may serve as standards
toward which we may strive with the satisfaction of
knowing that extremely good and thorough work has
been done if they are attained.
It will be desirable, now, to review the literature of
the frequency of irrigation, and see how actual practice
in various parts of the world corresponds with the
conclusions stated.
In southern Europe, wheat is irrigated three to four
times; in India, five times during the hot seasons and
four times for the crop of the cool season. In the
United States, Colorado irrigates two, three and, occa-
236 Irrigation and Drainage
sioually, four times, two being the usual number ; in
New Mexico, the ground is irrigated once before and
once after seeding and five times later, making seven
times in all ; while in Utah the number of waterings is
three to five.
The average number of irrigations appears to be
from three to five for wheat in all parts of the world.
But it should be understood that these irrigations are,
in all cases, supplemented more or less with natural
rainfall. In Colorado, for example, where the usual
number of irrigations is two, the rainfall from April 1
to July 1 is often as great as 8 inches, or two-thirds
the amount of water required for a yield of 40 bushels
per acre, thus making the number of irrigations amount
practically to six rather than two, and the mean interval
16% days, instead of 33 to 20.
It must be remembered, further, that while the
irrigations of wheat are in all eases supplemented with
natural rainfall, the yield per acre does not average 40
bushels ; hence the agreement of the theoretical fre-
quency of irrigation, 33 to 20 days, with that actually
practiced is more apparent than real.
In Egypt, maize is irrigated every 15 days, which
would make seven waterings for the crop. Barker states
that six irrigations are given to a crop in the Mesilla
valley. New Mexico; while in Italy three is the usual
number. But here, again, the spring and early summer
rainfall is quite large; so large, indeed, that much maize
is grown without irrigation. It appears, therefore, that
^here this cro-p must really depend upon u-rigation
for the water needed, it must be applied as often as
Frequency of Irrigation 237
every 15 to 20 days, and our experimental studies place
it at 15 to 27 days for yields of 100 bushels per acre.
The intervals between the irrigations for other
cereals will be found to fall between those for wheat
and maize, oats requiring the largest amount of water
and barley the least, to mature a large crop.
In the irrigation of clover and alfalfa, the usual
practice is to irrigate once for each crop. But there is
little question that larger yields for each crop may be
secured where the number of irrigations is doubled,
giving six where the number of crops is three, and ten
where it is five, thus making the length of the interval
10 or 20 days.
With other meadows, the general custom is to give
these as much and as many waterings as the water
supply will permit. In Italy, the summer meadows are
watered every 14 days. In southern France they are
watered every 5 to 18 days, and on the average every
10 days. Winter water meadows, as has been stated,
are watered with a nearly continuous flow of water over
their surfaces.
With potatoes, the custom is usually to depend upon
the natural rainfall to bring the crop nearly or quite
to blossoming, and then to irrigate twice on nearly
level fields, and three to four times where the slopes are
steep or where the soil is very porous and coarse in
texture, thus making an interval for this crop of 20
to 40 days.
For this crop our experimental studies indicate that
8.24 acre- inches may produce 400 bushels per acre ;
hence, that two to four irrigations might be sufficient
238 Irrigation and Drainage
for a full season, starting with the ground in good con-
dition as regards moisture at time of planting, making
the possible interval 33 to 65 days.
Fruit trees in Sieil}^ and southern Italy are watered
12 to 25 times during one season or once every 7 to 14
days. The peach and apple in Mesilla, New Mexico, are
watered once at the beginning of winter, once early in
January, and four or five times between April 1 and
September 30, thus making the interval for the growing
season 30 to 40 days. In Algeria and Spain, oranges
are irrigated the j'ear round — everj- 15 days in spring
and summer, but at longer intervals the balance of the
year ; and it is only on the heavy soils that irrigation
is dispensed with during the rsiny season. Grapes,
when irrigated, are usually watered every 10 to 20
daj's, and young vineyards oftener than those more
mature.
Rice in Italy is kept flooded from the time of
seeding until the plants are coming into bloom, and
then the water is di*awn off, but the fields are irrigated
afterwards every few days. In Egypt the water in
the rice basins is changed every 15 days, and in India
a crop of rice gets as many as twelve waterings.
In South Carolina, Mr. Hazzard informs me that
their custom is to clay the seed to prevent it from
floating, and then to flood the fields, keeping them so
until the rice is well up, when the water is drawn off
for 3 days to allow the plants to become rooted in
the soil, when the fields are again flooded for 3 weeks,
but changing the water everj'' 7 days. The water
is again drawn off for 30 days, to give the fields two
Measurement of Water 239
dry hoeiugs, wlieu flooding is again resorted to and
maintained until the crop is matured.
THE MEASUREMENT OP WATER
The man who has become expert in handling water
for irrigation really needs no means for measuring
the amount required for the watering. His judg-
ment, based upon an examination of the soil, is more
reliable as to when enough has been applied than any
measurement which could be made. But as soon as
the same source of water becomes the joint property
of a community, or wherever water is sold to consumers,
means for measurement and division become indis-
pensable. For the user of water, too, a definite knowl-
edge of the exact amount he is putting upon a given
area of land is very important, until he comes to know
the needs of his land and of his crops for water ; be-
cause without this knowledge he is liable to run on
for years, using too much or too little water, leading the
water too slowly or too rapidly through the furrows,
causing waste by deep percolation or too shallow wet-
ting of the soil. If he knows tliat he has put the
equivalent of 3 inches of water upon his field and only a
quarter of the surface has been wet, it is certain that
his method has been faulty and a large part of the
water used has been lost.
UNITS OF MEASUREMENT
From the standpoint of the agriculturist, there is
no unit for the measurement of water used in irrigation
240 Irrigation and Drainage
so satisfactory as one which expresses the depth of
water to be applied to a unit area, and the acre -inch
for English-speaking people, or the hectare -centimeter
for those who use the metric system, should become
universal. Rainfall is now uuiversally measured in
units of depth, and, as irrigation is intended to make
good deficiencies of rainfall, it would simplify- matters
greatly if the irrigator could call for the depth of water
he desired.
An acre-inch is enough water to cover 1 acre 1 inch
deep; and 10 acre -inches of water is enough to cover 1
acre 10 inches deep, or 10 acres 1 inch deep. As an
acre contains 43,560 square feet, 12 acre-inches is equal
to 43.560 cubic feet of water, and 1 acre -inch equals
one -twelfth of this amount, or 3,630 cubrc feet. As
there are 1,728 cubic inches in a cubic foot, and 231
cubic inches in a gallon, 1 cubic foot equals 7.48+
gallons, and 1 acre -inch equals 27,150 gallons.
As 1 cubic foot of water at 60° F. weighs 62.367
pounds. 1 acre -inch equals 226,392 pounds, or 113.2
tons of 2.000 pounds.
Another measure frequently used in the gauging of
streams, and also used as an irrigation unit, is the
second-foot, which means a discharge or flow of water
equal in volume to 1 cubic foot per second of time;
and a stream having the volume of 1 second -foot would
supply an acre -inch in 3,630 seconds, or in 30 seconds
more than one hour. In 24 hours, a stream of 1
second-foot would supply 23.8 acre -inches, and would
cover 7.93 acres of land with water 3 inches deep.
Still another unit in common use in the western
Measurement of Water 241
United States is the miner's inch, which is the amount
of water which may flow through an opening 1
square inch in section in one second under a certain
pressure or head. But the legal pressure varies in
different states ; hence, the miner's inch has not a
fixed and definite value. In California 50 miner's
inches are usually counted equivalent to 1 second-foot,
while in Colorado only 38.4 statute inches are required
for a second -foot.
Where a larger unit of measure is desired than
either of those named, the acre -foot is sometimes
used. This is an amount of water required to cover
an acre 1 foot deep, and is, therefore, equal to 12
acre -inches.
METHODS OF MEASUREMENT OF WATER
Much and long as irrigation has been practiced, and impor-
tant as the subject is, especially in communities where water
is scarce and where each user has need of every drop of water
he can get, there appears even yet to have been devised few
methods of measuring or of apportioning water among the users
which possess the degree of precision which could be desired.
In the case of individual irrigators, where the water is
pumped and stored in reservoirs, to be used as desired, the area
of the reservoir and the amount the water is lowered in it fur-
nish the needed data for determining the amount which has
been applied to a given area of land. Or, in the case of direct
application of the water pumped to the land, the rate of the
pump may be known, and thus, through a knowledge of the time
of pumping, furnish an approximate measure of the water used.
In the great majority of eases, however, a knowledge of the
amount of water used in irrigation must be gained in some other
way.
242
Irrigation and Drainage
The Method of Time Division
Where the amount of water carried in a ditch, lateral or
pipe is not so large but that an individual may use the whole
of it to advantage, the usual and the simplest method of divid-
ing the water is on the basis of time, allowing each user to
have the whole stream a specified number of hours and minutes,
making the length of the time proportional to the amount of
water to which each user is entitled.
"With this method, it is customary to issue to the various
users under the ditch, at the beginning of the irrigation season,
printed schedules or tickets, covering the whole or a portion of
the season, which specify the dates upon which they will be
entitled to the use of water, and the length of time they can
have it, as illustrated by the following ticket :
i WATfiR TICKET NOJUil
T r#trftJ*tJ*T jftrft jfti_s*t rfufcjt-uCi AjCtjCi-^i
jiW 0^..3^.../0^,:Z^....
DISTRICT m/^-.- -DITCH N0-(^..
Spnngville. U^ai)...C^^^zt^„^Z 1896]'
V«t( mp» antltUd to tha as* ot tl
> J^^ . day of _^;?S&r^t^ ._
JSJ2.
^^^^--H^^
i tben |i«qulF*d to dU
» j{i z;i v^i T^r j{t j;«-j;r7{s ^}t jjtt;! j;s -jjv J^I-JJS ^ :i:s -jp^ ip Tji 3J> 7;r 7^ 7}s-J:s-j;iTji-
ts us* and turn It off your l«Bd>
WALTER BIRD, W*t*l<mast*r.
With this system, if one man is entitled to two, three or
four times the amount of water that a neighbor is entitled to,
the length of his period is two, three or four times as long;
and, as shown by the ticket, a regular rotation is followed, the
water returning to the same user after the same number of
days.
Where the water must be used day and night, as should be
the case where water is scarce and is allowed to run continuously
to reduce waste, in order to prevent the night use of water fall-
ing always upon the same individuals, the rotation period may
Measurement of Water
243
be made to include a fraction of a day, say 8)4 days instead of
8, as in the one cited ; or, after a certain number of rotations,
the water may be given first to a different member in the
circuit, and thus change the time of day at which each gets
his turn.
In those cases where the supply of water in the ditch is
always the same, this is the most accurate and best method of
dividing water which has been devised, and where the amount
of water which the ditch carries is known, it gives every one a
definite knowledge of the amount of water he is using.
It often happens, however, that the volume of water changes
from time to time, and when this is true those who chance to
be using water when the supply is high will receive most.
But if the period of rotation is short, the injustice will seldom
be very great, and where the periods of rotation are short, the
service is usually more convenient and better for other reasons
than that of a more equitable division of the water, because it
permits a user to apply his water to certain fields one date and
to another on his next turn, thus permitting him to do his fit-
ting and cultivation between irrigations to a greater advantage.
The Subdivision of Laterals
Where the lateral carries too much water to be used to
advantage by single indi-
viduals, this may be sub-
divided readily into two
exactly equal portions, and
these two divisions may
be again subdivided into
two precisely equal streams.
But in order that the di-
vision may be exact, it
must be done in certain
^
^^
\7
Fig. 43. Branching of canal to divide water
equally (A and B) and unequally (O).
ways, as represented in Fig. 43. If the two branches of the lateral
form equal angles with the main, have the same fall, and their
bottoms at the same level where they start, they will carry equal
244 Irrigation and Drainage
volumes of water if their dimensions are exactly the same as
shown at A and B. But if the division is made as at C, or in
any other manner, which makes the two arms in any way
unlike, one will carry more water than the other. So, too, if
care i^ not taken to keep the main and the two branches clean
where the division is made, it will not be exact.
When an effort is made to divide the main into two unequal
parts, or into an odd number of equal parts, the task becomes
an extremely difficult one, and one which is not likely to be
accomplished, and the attempt should be avoided.
The cause of the difficulty is found in the fact that the water
travels with the greatest velocity in the center of the stream
and diminishes in speed as the sides are approached, so that if
the main is divided into two branches which have cross-sections
in the ratio of 1 to 2, the larger arm will carry more than twice
the amount of the smaller one, because it must take a larger
share of the water moving in the central portion of the main.
Or if the main is divided into three equal laterals, then the
central branch is sure to carry more water than either of the
two taking the water from nearer the sides, and it is not prac-
ticable to so adjust the dimensions of these branches that with
varying volumes of water moving in the main the desired ratios
shall always be secured in the divisions.
The Use of Divisors
When it is desired to remove from a ditch a certain portion
of the amount of water which it is carrying, this is sometimes
attempted by means of an arrangement represented in Fig. 44,
called a divisor, in which the portion A is set into the channel
some fractional part of the whole width, determined by the
amount which it is desired to take out. Thus, if it was desired
to take out one-fifth of the stream, and the lateral had a width
of 40 inches, the divisor would be set in toward the center 8
inches. But from what has already been said, it follows that
less than one-fifth of the water can thus be removed, for the
two reasons, that the section of the stream removed does not
Fig. 44. One form of water divisor.
JDivision of Water 245
have the mean velocity of the part remaining, and, having to
change its direction to one at right angles, its velocity is still
further cheeked in making the turn. The smallest users of water
by this system, therefore, in- ., ■
variably receive an amount >-y^
which is less than they are "
entitled to use, while the larger 1 V
users receive more. In order
to reduce this inequality of
division, the practice of insert-
ing a weir-board in the canal
just above the divisor, so as to
restore a more nearly equal velocity across the stream, is some-
times adopted; and if the canal is broadened above the measur-
ing-box, so that the water approaches the weir slowly and passes
over it smoothly without contraction, Carpenter states that the
method will give as satisfactory results as any with which he
is acquainted.
The Use of Modules
A module is defined as a means of taking out of a canal a
definitely specified quantity of water, measured as so many inches,
cubic feet per second, or other units, rather than the simple
division of a stream into a certain number of parts, as is the
case where the divisor is used.
Two types of modules are employed, one based upon the
principle of the weir as a means for measuring water, and the
other on the laws governing the flow of water through orifices.
If it were readily practicable to establish and maintain any
desired pressure at a weir or an opening, water could be appor-
tioned for irrigation with satisfactory precision with the aid of
modules, but no method for doing this has yet been devised,
although much study through many centuries has been devoted
to it.
The spill -box, invented by A. D. Foote, and represented in
Fig. 45, is, perhaps, as satisfactory a means for maintaining a
246
Irrigation and Drainage
nearly uniform head against either a weir or an opening as has
yet been devised. Its essential feature is a long, sharp lip,
over which the water may spill back into the canal in a thin
sheet, and thus maintain a nearly constant pressure back of
Fig. 45. Spill-back method of dividing water.
the lip of a weir or above an opening. But this arrangement
does not and cannot maintain a constant pressure where there
is any considerable fluctuation in the volume of water in the
main canal; and, since the depth of water above the opening
or lip of the weir must always be small, even a slight change
Division of Water 247
in the depth of the water over the lip of the spill -back must
make a perceptible difference in the discharge.
Further than this, where the form of the opening is designed
to be made longer or shorter by means of a sliding valve accord-
ing as more or less water is desired, the amount discharged,
even when the head is maintained rigidly constant, is not
directly proportional to the length of the opening, because the
number of inches of margin upon which the resistance to flow
depends does not maintain a constant ratio to the cross -section
of the opening. The more margin there is in proportion to the
area of the opening, the greater must be the loss of discharge
through friction and contraction, so that the most exact and
generally satisfactory way of apportioning water among users
which has yet been devised, is that of bisecting the stream until
its volume has become suitable for individual use, and then sub-
dividing by time under some system of rotation.
CHAPTER VII
TEE CRABACTEB OF WATER FOB IBBIGATWN
The characteristics which determine the suitability
of water for the purposes of irrigation must depend
upon the chief objects for which the water is used :
whether it is to control temperature, as in the case of
winter -meadows and in cranberry culture ; to supply
plant -food, as in the case of summer water-meadows ;
to meet the simple need of water for the transpiration
of the growing crop, or to deposit sediments for the
purpose of building up the surface of low -lying areas,
as in the case of warping.
TEMPERATURE OF WATER FOR IRRIGATION
Where one of the prime objects in the use of water
for irrigation is to stimulate plant -growth, the warmer
the water is within the natural ranges of temperature
the better are the results. According to Ebermayer,
when the temperature of the soil in which a crop is
growing has been lowered to from 45° to 48° F., phys-
iological processes are brought nearly to a standstill
in it, and the maximum rate of growth does not be-
come possible until after the soil temperature has
risen above 68° to 70°. It is plain, therefore, that if
large volumes of cold water were applied to the soil at
(248)
Temperature of Water for Irrigation 249
one time, and especially if a flooding system were
adopted by which the cold water were kept moving
over the ground in the growing season during several
days, the temperature of the soil might easily be
brought so low as to seriously interfere with normal
growth.
The dangers, however, from using cold irrigation
waters are not as great as might at first be supposed;
and it is seldom, where good judgment is exercised, that
the low temperature of the water of wells and springs
need prohibit its use for the purposes of irrigation.
In the first place, there are few cases where the
temperature of well or spring water during the irri-
gation season will be found as cold as 45° F., the
more usual temperature being nearly 50° or above.
In the second place, water warms very rapidly during
bright summer days, when spread over the surface
of the ground, or when led along furrows, and even
while flowing through ditches, for it absorbs the direct
heat from the sun readily, as the rays of light pene-
trate it, and is further indirectly warmed by the
balance of the sunshine which, passing through the
water, is arrested by the dark soil beneath. While
the water is flowing over the surface of the ground,
if its temperature is below that of the soil, it really
stores much heat which otherwise would be lost, be-
cause relatively much less will be lost by radiation
from the hot surface of the soil and stored in the
water, leaving less to pass away from the dry ground
whose immediate surface becomes very warm, and
hence fitted to lose heat rapidly.
250 Irrigation and Drainage
In the third place, the temperature of the surface
foot of soil in the daytime of midsummer, with its
contained moisture, is usually as high as 68° to
75°, and to lower its temperature 1° F. requires the
absorption by water added of from 25 to 40 heat units,
according as the soil varies from a nearly pure sand,
weighing 110 pounds per cubic foot, and containing
4 per cent of water, to a humus soil, containing 30
per cent of water and 50 pounds of dry matter per
cubic foot.
One heat unit is taken as the amount needed to raise 1
pound of water at 32° to 33° F. With the relations stated, it
appears that 4 inches of water having a temperature of 45° F.
applied to a field having a soil temperature of 75° might lower
the surface foot to 65° or 61.7°, according to the specific heat of
the soil ; and with a soil temperature of 68°, the lowest tem-
perature the 4 inches of water could produce would range be-
tween 60° and 57.6°. But this assumes that the water is applied
at once, with no opportunity for warming until it is brought into
contact with the soil, which, of course, cannot be the ease. If
the irrigation water has a temperature of 50° F., then the lowest
degree 4 inches of water could force upon the surface foot of
soil would be some amount above 66.7° to 63.7° when the origi-
nal soil temperature was 75°, or 62° to 59.9° if the initial soil
temperature were 68° F.
The results summarized on page 214 indicate that the mean
amount of water used in single irrigations is at the rate of 2.02
inches once in 10 days. Hence, were the coldest water used in
this quantity, the greatest depression of the temperature of the
surface foot could not exceed 6.7° F. This assumes that neither
the water nor the soil receives any heat during the time the
water is being applied. It is clear, therefore, that where good
judgment is exercised in the application of either well or spring
water, it may be used without in any serious way interfering with
normal growth. The chief danger will, of course, lie in the ap-
Fertilizing Value of Water 251
plication of excessive amounts of water, when injury would fol-
low certainly, and sooner than where warmer water is at haud.
Warm water is better than cold, and in making a choice of
waters it is, of course, best to select the warmest where this can
be done. But the point we wish to emphasize is, that well and
spring water and mountain streams may be used to advantage
for irrigation where warmer water is not at hand. Mr. Crane -
field* has experimented with tomatoes, radishes and beans grown
in a greenhouse and in the garden, irrigated with water at 32°,
and has found them to do nearly as well as those given water at
70° or 100°.
The writer waters his own garden and lawn directly from a
well with water having a temperature of 48° to 50° F., and the
present year we cut with a lawn mower, on 21,869 square feet
of lawn about the house, between May 6 and November 5, enough
grass to feed one cow all she needed for 95/^ days. On 90,709
square feet, including the lawn, or 2.08 acres, we this year fed,
by soiling, two cows and one horse from May 6 until November
5, and put into the barn besides 4.75 tons of hay, .14 acres of
this ground being in Stowell's Evergreen sweet corn. Three crops
of clover were cut from the same ground, and the third cutting,
November 1, averaged a ton of hay per acre, and was a little
past full bloom, and yet the watering was done directly from,
the well with water at 48° F.
FERTILIZING VALUE OF IRRIGATION WATER
In traveling from place to place in Europe, it was
a continual surprise to the writer to learn from those
who were using water for the irrigation of meadows
that the fertility which the river waters added to the
soil was generally regarded as the chief advantage
derived from them. The vast volumes of water which
are sometimes used for this purpose have already been
cited.
♦Fifteenth Ann. Rept. Wis. Agr. Exp. Station, p. 250.
252 Irrigation and Drainage
As an example of the amount and kind of material
-which would be added to the laud where what is re-
garded as exceptionally pure water is used, we com-
pute from the results of analyses of the water of the
Delaware river* the amount of material contained in
solution in 24 acre-inches, as follows:
Materials in 24 acre-inches or Delaware river water
Pounds
Calcium carbonate 242.6
Magnesium carbonate 166.16
Potassium carbonate 31.74
Sodium chloride 20.54
Potassium chloride 1 .86
Calcium sulphate 35.48
Calcium phosphate 26.14
Silica 93.34
Ferric oxide 5 6
Organic matter containing ammonia .... 117.62
Total 741.08
The average amounts of nitrogen compounds, as
computed from the chemical analyses of the waters of
twelve streams in New Jersey, are as follows:
Nitrogen Compounds dissolved in 24 acre-inches of water from 12
streams in Xew Jersey
Pounds
Free ammonia 15.63
Albuminoid ammonia . . .^ 81.12
Nitrates 772.67
Nitrites .86
Total 870.28
*Rept. New Jersey Geol. Survey 1868, p. 102.
iSewage Waters for Irrigation 253
Using the figures of T. M. Read* regarding the
amonnt of materials which the great rivers of the
world bear in solution to the sea, it appears that the
Mississippi and St. Lawrence rivers, in North America,
and the Amazon and La Plata, in South America,
carry an amount such that the average is 655.6 pounds
per each 24 acre- inches of water.
Goss and Haret, from analyses of the water of the
Rio Grande at different periods from June 1 to Octo-
ber 31, compute that 24 acre-inches of the water
contained in sediment and in solution 1,075 pounds
of potash, 116 pounds of phosphoric acid, and 107
pounds of nitrogen. The water of this river contains
a sufficient amount of sediment so that 24 acre- inches
of it furnishes 81,309 pounds, or more than 4 tons-
per acre.
It is evident from these data that the ordinary
clear waters of rivers, lakes, springs and wells cannot
be expected to bear to the fields upon which thej' are
applied a sufficient amount of plant -food to meet the
needs of crops, unless the water is applied in much
larger volumes than is required to meet the demands-
of soil moisture.
SEWAGE WATERS FOR PURPOSES OF IRRIGATION
It may be laid down as a general rule that the
water of highest value for the purposes of irrigation
is the sewage of large cities, unless it contains too
*Am. Jour. Sei., vol. xxix., p. 290.
tNew Mexico Expt. Sta., Bull. 12.
254 Irrigation and Drainage
large amounts of poisonous products from factories
in the form of injurious chemical compounds.
The organic matter of sewage, in both its soluble
and finelj" divided, suspended form of solids, when
sufficiently diluted with other water, is of the highest
value as a fertilizer for many crops, and in all
warm climates it is often practicable and very de-
sirable to use such water for this purpose.
Reference has already been made to the use of
sewage waters from the city of Milan on the water-
meadows of Italy. The far-famed Craigentinny
meadows, outside of Edinburgh, are another emphatic
illustration of the value of sewage in the production
of grass, and Storer, after visiting them in 1877,
wi'ites as follows :
"In 1877 there were 400 acres of these ' forced
meadows ' near Edinburgh, and they ai-e said to in-
crease gradually. The Craigentinny meadows, just
now mentioned, were about 200 acres in extent, and
they had then been irrigated 30 years and more.
They were laid down at first to Italian ray grass
and a mixture of other grass seed, but these arti-
ficial grasses disappeared long ago, couch-grass and
various natural grasses having taken their place.
The grass is sold green to cow -keepers, and yields
from $80 to $150 per acre. One year the price
reached $220 per acre. They get five cuts between
the 1st of April and the end of October. This farm
of 200 acres turns in to its owner every year $15,000
to $20,000 at the least calculation, and his running
expenses consist in the wages of two men, who keep
Setvage Waters for Irrigation
255
the ditches in order. The sewage he gets free. The
yield of grass is estimated at from 50 to 70 tons
per acre."
lu 1895, 18 years later, the writer visited the
meadows described above, and Figs. 46 aud 47 were
taken at the time. The first figure shows a load
of grass, estimated to weigh 2,500 pounds, cut to
feed 23 cows during one day, from an area of 2,734
square feet. Seven acres of this grass had been
purchased to feed the herd of 23 cows from May 1 to
Fig. 46. Two thousand five hundred pounds of grass cut on 2,734 sq. ft.
of Craigentinny Meadows, Edinburgh, Scotland.
October 20, during which time the grass would be
cut four or five times, and the price paid for this
grass, sold at auction, varied from $77.44 to $111.32
per acre, according to the quality of the several plots
making up the seven acres purchased. The increase of
these meadows about Edinburgh, it was said, was
tending to lower the price which this grass could
256
Irrigation and Drainage
eoimnand, but the superiutendeut informed me that
during the past twentj' years the average price per
acre for the whole estate had been $102.20. Yet
this grass is cut by the purchasers and hauled three
Fig. 47. Distribution of sewage on Craigentinny meadows, Edifibtirgh,
Scotland, just after cutting grass.
to four miles day by day to feed their cows, stabled
and milked in the crowded business portions of
the cit}-.
When it is further stated that much of the land
upon which this grass is now grown, and has been
continuously grown for nearly a century without
rotation, was originally a waste sandy sea beach, it
will be the better appreciated how valuable is such
sewage water for the purposes of irrigation.
Regarding the healthfulness of milk produced from grass
grown under sewage irrigation, statements like the following
are repeatedly being made : "The only question is, whether
there may not remain adhering to grass which has been bathed
Sewage Water for Irrigation 257
with sewage some germs of typhoid, cholera or other vile disease
which are propagated in human excrement ; " and in view of
what is now known regarding the nature of such diseases, it
is not strange that such fears should arise in the minds of
sanitarians.
But in view of the fact that milk has been produced from
such feed for nearly a century immediately within the city of
Edinburgh, the sewaged grass traversing the streets daily during
the whole season in sufficient quantity for several thousand cows,
and the milk so pi-oduced wholly consumed by its people with-
out protest, must be taken as the safest possible evidence
that there is practically little danger in this direction ; and
when it is remembered that the large city of Milan, Italy, has
been supplied with milk produced from such grass fed the year
round for more than two centuries, the evidence against the
fear expressed is more than doubly strong, coming, as it does,
from a warm southern climate and covering so long a period.
The question, however, is still discussed, and in order that
there may be no tendency to throw public vigilance off its guard
in so grave a matter, we quote from the Edinburgh Evening
Dispatch of July 5, 1895, parts of a discussion which was being
had at the time of my visit, as follows:
"Last week we called attention to the peculiar tactics
adopted by some medical gentlemen, sanitarians and others, who
are attempting to float a new dairy company. * * * One of
the strategic movements of these 'philanthropic' speculators was
to try and create a prejudice against the milk produced in the
Edinburgh dairies, on the ground that the cows were largely
fed on sewage grass during the summer. In regard to this, we
pointed out that the royal commission which investigated the
whole subject of sewage farming some years ago, reported that
they had failed to discover a single case where injury to health
had resulted from the use of milk drawn from cows fed on
sewage grass. Since our article on the subject appeared last
week, our attention has been called to some further evidence
which fully confirms the conclusions at which the royal com-
missioners had arrived. In his evidence given before the Rivers
258 Irrigation and Drainage
Pollution Commissioners, the medical officer of health for Edin-
burgh, Dr. Littlejohn, now Sir Henry Littlejohn, said:
" 'The cows in Edinburgh are chiefly fed with sewage grass
that is grown on Craigentinny meadows. I have thought that
there might be objection to feeding cows upon grass so grown,
because I was of opinion that grass so grown might be of inferior
quality. But practically I have failed to detect any bad effects
resulting from the use of such grass.'
" Another point which these philanthropic sanitarians tried to
make out against milk from sewage -grass -fed cows was that
such milk 'turned putrid in a very short space of time.' The
most ample evidence is forthcoming to show the absolute ground-
lessness of this contention also. Mr. Spier, the Scottish Dairy
Commissioner, who has conducted most of the dairy experiments
which have been carried on for the Highland Agricultural
Society, has fully tested the matter, and he writes to us as
follows on the subject:
" ' By way of testing this point, I set aside eighteen cows for
the experiment: Of these, six were fed in the house on sewage
grass, six were fed in the house on vetches, and the other six
were pastured in the fields. Milk from each of these sets of
cows was repeatedly set aside in separate vessels until it became
decidedly tainted, and out of the numerous tests the milk from
the cows fed on sewage grass never once turned sour first. In
the majority of cases, the milk from the cows fed on the vetches
was the first to turn sour, while the milk from the sewage grass
and on the pasture was about equal in keeping properties. On
several occasions the milk from the three lots of cows was kept
for the same length of rime and churned separately, but on no
single occasion did the butter from the cows fed on sewage grass
become rancid before the other lots did. Samples of the butter
from the three different lots of milk were sent to the chemist
of the society, and he was unable to tell which was which. ' "
These statements will serve to call attention to the fears
which have been expressed on theoretical considerations, and
the nature of the evidence which appears to indicate that there
is little ground for them.
Value of Turbid Water 259
THE VALUE OF TURBID WATER IN IRRIGATION
Next in value to warm sewage water for irrigation
must be placed that of streams carrying considerable
quantities of suspended solids. It is generally recog-
nized that the richest and most enduring soils of the
world are those formed from the alluvium of streams
laid down by the water on its flood plains, and
reworked many times over as the stream shifts its
course from side to side in the valley; and when this
is true, it will not be strange that the water of turbid
streams has genei^Prlly been held in great esteem for
irrigation, on account of its high fertilizing value.
In the case of the Rio Grande river, Goss has
shown that the application of 24 inches of this water
would add nearly one -quarter of an inch of soil to
the field in the form of river sediment, and that this
sediment would contain per acre 1,821 pounds of
potassium sulphate, 116 pounds of phosphoric acid
(P2O5), and 107 pounds of nitrogen. Four years of
irrigation at this rate would add an inch of soil to
the field, and 24 years would cover it 6 inches deep
with a sediment containing three times the amount
of potash found in the average clay soil, and the same
percentage of phosphoric acid and a high percentage
of nitrogen.
When such sediments are laid down upon coarse,
sandy soils, it will be readily appreciated that the
gain to the field is far greater than that due to the
mere plant -food which the sediments contain; for such
sediments, being composed of very fine grains, their
260 Irrigation and Drainage
influence in improving the texture of the soil is quite
as great as that due to the fertilizers contained.
The sediment carried by the Po is given by Lom-
bardini as tott of the volume of the river, and on
this account the waters are held in high esteem for
irrigation.
The river Nile, during the time of the rainy season
of mountainous Abyssinia, comes loaded with sedi-
ment constituting 6-7T of the volume of the water;
and this, under the old system of the Pharoahs of
basin irrigation, which permitted the rich mud to col-
lect on the fields, kept them fertile for thousands of
years, and they are so today; whereas in Lower Egypt,
where the old practice has been abandoned in recent
years for an "improved" system, which does not per-
mit the utilization of the rich Nile mud, the fields are
fast deteriorating in fertility, although only half a
century has passed.
The Durance, in France, is famous for its fertile
waters, and they carry at the ordinary maximum -gV of
their weight of sediment, or nearly 1.9 pounds per
cubic foot, equal to 82,464 pounds per each acre-foot
of water. In rare cases the sediment of this stream
rises to iV of the water by weight, and the average
proportion for nine j'ears has been found to be tsT.
When such waters are used year after year on poor
lands, the improvement becomes very great, while on
the better lands a high and permanent degree of fer-
tility is maintained indefinitely, with heavy yields per
acre as the result.
Improvement of Land by ISilting 261
IMPROVEMENT OF LAND BY SILTING
Nature's method of depositing the fine silt borne
along by streams, whenever they overflowed their
banks, early suggested the idea of directing this work
so that the materials should be laid down on sandy
or gravelly soils, to so improve the texture and fer-
tility as to convert comparatively worthless areas into
extremely productive lands.
In other cases, where marshy, low -lying lands, or
shallow lakes and estuaries were lying adjacent to
turbid streams, the waters have been so turned upon
them and then led away as to lay down mantles of
rich soil of sufficient thickness to raise the surface to
such a height as to permit of drainage, and thus
reclaim worthless swamps, converting them into rich,
arable fields.
In England, where the method was introduced
from Italy to reclaim waste lands near the sea, the
process is called "warping," and in France "colmatage."
In England, as on the Humber, where the tides rise
several feet, and the waters of the river are turbid,
much land has been reclaimed by warping. Centuries
ago low, flat lands were dyked off from the sea to
prevent inundation; but in more recent years, to
this improvement was added the one under considera-
tion. Tide sluices, provided with gates to admit
the turbid water held back by the sea, were set in
the dykes, and the low lands were laid out in fields
surrounded by banks for retaining the water until
the sediment borne in upon the area should have time
262 Irrigation and Drainage
to settle, when the clear water returned to the stream
with the fall of the tide.
So large was the amount of sediment carried in
the water, and so rapid was the silting -up, that fields
of 10 to 15 acres are said to have been raised from
one to three feet dui-ing a single season, thus convert-
ing worthless peat bogs in so brief a time into fields
of the richest soil. One season spent in warping,
one for the gi-ound to settle and become compacted,
and a thii-d to get it into grass, is the usual time
required for reclamation, and after this such fields
produce enormous crops of almost any kind suited to
the climate. In other regions, where less sediment
is carried in the water, or where greater depths of
silt must be laid down in order to secure the desired
levfl of the surface, longer time is required for the
work, but in Italy fields have been raised as much
as 6 to 7 feet in 10 years.
In other portions of the world, notably in the
Nile valley, a modification of this system of silting
for the yearly enrichment of the soil is practiced.
To this end the ancient ii-rigators, both in upper and
lower Egypt, had laid out the accessible lands for
basin irrigation, by which the tui'bid and fertile waters
of the Nile, at its flood season, could be led upon the
settling areas and held until the rich sediments were
laid down, thus converting otherwise comparatively
worthless sandy soils into the richest and most de-
sirable of fields, and so maintained for thousands of
years by periodic inundations.
Then, again, in France, as in the Moselle valley,
Improi-ement of Land by Silting
263
and in the district of the mouths of the Rhone,
between Aries and Mirimas, for example, on broad,
flat plains of extremely- coarse gravel, ^yhere in earlier
years the uncontrolled waters have permitted no soil
to form, this sj'stem of silting, "colmatage" or
Fig. 48. Head-gate on the Durance above Avignon, yruuft
"warping," has been introduced, and rich deposits
laid down among and above the coarse materials,
until productive fields, orchards and gardens have
taken the place of wide reaches of naked gravel
beds.
Fig. 48 is a head - gate on the Durance, above
Avignon, where a portion of the water of the district
is taken out. The soil here, for depths exceeding
10 feet, as shown by cuts observed, is made up, seem-
264 Irrigation and Drainage
ingly, of 70 per cent of coarse gravel from Xinch
up to 4 aud 5 inches in diameter, and a surprisingly
large per cent is composed of the larger sizes. Among
this gravel the river silt has been deposited until
fields of alfalfa and wheat, as well as gardens and
almond orchards, are grown upon these extremely
pervious beds.
OPPORTUNITIES FOR SILTING IN EASTERN
UNITED STATES
East of the Mississippi, extending from Wiscon-
sin through Michigan, New York, and into New
Jersey, as well as in New England, there ai^ exten-
sive areas of very sandy lands which, if they were
subjected to this process of silting, so as to render
them less open in texture, and to increase the per
cent of plant -food they contain, would become pro-
ductive and very desirable lands. At present they
are gently sloping sand}" plains, bearing a scant vege-
tation, but J) resenting ideal slopes for irrigation, and
very many of which are so situated that water could
readily be led upon them, both for silting purposes
and for permanent irrigation, at relatively small cost.
Then, again, in the southern states, notably in the
Carolinas and Georgia, there are vast areas of sandy
soil which stand greatly in need of such improvement
as flooding with silt -laden waters could bring about.
These lands possess surface features and slopes which
readily permit of this being done ; and, what is more
to the point, the streams are abundant aud heavily
Improvement of Land by Silting 265
laden with silt which thej' are carrying out to sea in
great volumes, thus robbing the Piedmont country at
a fearful rate, through lack of sufficient care, of its
most fertile soil, and transporting it directly through
the fields to which it should be applied and upon
which it could readily be led to great advantage.
On the sea coasts of these three states, and par-
ticularly in South Carolina, there lie those extensive
and once wonderfully productive rice fields upon which
so much labor and capital have been spent, but which
are now largelj' abandoned, since the war of the re-
bellion, for the lack of sufficient energy to bring the
needed capital to the region.
Here are opportunities for capital to find splendid
permanent investment at good rates of interest, to
reclaim the vast rice fields now fast falling into ruin,
and to apply the methods of warping to these and
other lands until they become what they may certainly
readily be made, both thoroughly healthful and the
richest of fields, adapted to a wide diversity of pro-
ductions. The opportunities for warping are better
nowhere in the world, and there must certainly be a
great future awaiting intelligence, energy and capital
here to work out the needed improvements.
ALKALI WATERS NOT SUITABLE FOR IRRIGATION
In many portions of the world, and oftenest in
arid and semi -arid regions, the waters of some
streams and wells, and particularly those of lakes,
are too heavily charged with the salts of sodium —
266 Irrigation and Drainage
common salt, sal soda and Glauber's salt or sodium
cliloride, carbonate and sulphate respectively — to
make it advisable to use them for the purposes of
irrigation.
These salts are a part of the waste products of
soil production which ordinary vegetation is unable to
use with profit, and which in countries of heavy rain-
fall are washed out of the soil nearly as rapidly' as
formed. Where these salts, however, do accumulate
to any notable extent, it is designated an alkali soil,
and will not produce normal crops of many of the
forms grown in plant husbandry. The general sub-
ject of alkalies and their treatment is discussed in
the next chapter, but we cite below the composition
of waters which have been regarded as safe and as
unsafe, without treatment, for purposes of irrigation:
Table of safe and unsafe alkali waters* in parts per 1,000
' Safe water ■
■ — Unsafe water —
No. of
sample
Black
alkali
White
alkali
No. of
sample
Black
alkali
White
alkali
740
.022
.067
739
.141
.135
742
.005
.306
741
.009
8.756
743
.007
.155
753
.026
.818
744
.022
.399
751
.011
7.374
755
.009
.334
746
.101
1.063
749
.026
.306
747
.115
1.082
750
.014
.111
757
.036
1.577
754
.026
.033
760
.132
.084
It is very unfortunate that after an analysis of a
sample of water has shown accurately the amounts of
various elements it may contain, it has not been pos-
'Oomputea from Bull. 29, p. 4, Oklahoma Exp. Sta.
Alkali Water not Suitable for Irrigation 267
sible to state with certainty precisely how these ele-
ments were eomhined in the sample. It is more
unfortunate that chemists are not agreed as to how
results should be interpreted, and that different sj'S-
teras are followed by different analysts. But what is
most unfortunate of all, is that many chemists have
published their computed results, as though there
were but one interpretation of them, and have not
given the data upon which their computations were
based. Hence, we have found it impossible to arrive
at what may be regarded as the safe amount of
black or white alkali an irrigation water may contain.
The table given above represents the opinion of two
chemists as shaped by their system of computing the
amounts of the alkalies in the samples analyzed, but
it must be understood that another chemist using the
same data, with a different system of apportionment,
would compute either less or more black alkali and
more or less white alkali than the authors have
credited the samples with as given in the table above.
We make this explanation, that the irrigator may
understand that when the water from a given source
is said to contain .022 parts in 1,000 of black alkali,
more allowance must be made in regard to accuracy
than is required for the statement that the water car-
ries in solution 11.234 grains of solids per gallon.
It should be understood further, as will be shown
in the nest chapter, that a given quantity of black
alkali may prohibit the use of the water for irrigation
purposes on one soil, when upon another it may be
used with perfect safety.
268 Irrigation and Drainage
It sometimes happens that waters draining from
swamp lands where there has been considerable stag-
nation, or where there are too strong solntions of
humic acids or salts of iron, are not suitable for irri-
gation purposes, and must be avoided. In portions
of Europe, too, there are streams used for irrigation
which are known as "good" streams and "bad"
streams. Crops irrigated from one produce heavier
yields than when irrigated from the other, and cases
are cited where the differences in yield are so large
that they can hardly be assigned entirely to difference
in the amount of plant -food carried by the two.
CHAPTER VIII
ALKALI LANDS
CHARACTERISTICS OP ALKALI LANDS
The use of the term "alkali lands," as commonly
employed, has quite a loose or wide application. Hil-
gard states that in California the term is applied
almost indiscriminately to all lands whose soils con-
tain unusual amounts of soluble salts, so that during
the dry season or after irrigation the surface becomes
more or less white with the deposits left by the evapo-
ration of the capillary waters. Throughout much of
Minnesota, Wisconsin, Michigan, and other states lying
within the glaciated areas of this country, there are
black marsh soils which, after being drained and
tilled, come to acquire in spots a deposit of white
salts at the surface whenever there is much evapo-
ration from the soil, and these are frequently spoken
of as "alkali spots." Where these salts are well
marked in character, crops are killed out entirely, or
the growth is stunted much as. is true of the black
alkali spots of arid regions. On the rice fields of
South Carolina, there appear during the dry stage
of growth of the crop "alum spots," as they are there
called, upon which the rice may die out or be of
inferior quality. Then, too, on the margins of the
(269)
270 Irrigation and Drainage
sea, where there are low-lj-ing lauds periodically in-
undated by high tides, white deposits are again left
when the surface becomes dry, and are injurious to
cultivated crops when they have accumulated to suf-
ficient strength, and these are sometimes spoken of
as "alkali lands."
In the wide application of the term, then, "alkali
lands" are those upon which soluble salts have ac-
cumulated in sufficient quantity', through evaporation
and capillarity, to attract attention by their usually
white appearance and their injurious effects upon
vegetation .
Hilgard states that "alkali lands must be pointedly
distinguished from the salt lands of the sea margins
or marshes, from which they differ both in their
origin and essential nature ; " and, in the sense he
wishes to be understood, the distinction should be
made ; but there are important advantages, as will
appear, in treating them all under one head.
CAUSE OF INJURIES BY ALKALIES
When the soil water about the roots of plants or
germinating seeds becomes suflBciently strong with
salts in solution, the osmotic pressure is so modified
that a discharge of the cell contents into the soil takes
place to such an extent as to produce what is equiva-
lent to wilting. The cells are not maintained suffi-
ciently turgid to permit normal growth, or they may
have the pressure so much lowered as to cause death.
The case is like placing the plump strawberry or
Cause of Injuries hij Alkalies 271
currant in a strong solution of sugar, where it is ob-
served to greatly shrink in volume. So, too, it is
like placing meat under strong brine, and the use of
sugar in preserves, where there is so strong a solution
about the products preserved that the germs of decay
cannot thrive in them.
This, then, is one of the modes by which the in-
jurious effects of alkalies are produced, and it should
be understood that it matters very little what sub-
stance may be in solution in the soil water, so long
as it is there in sufficient quantity to produce the
osmotic shrinkage referred to.
Every one is familiar with the fact that too con-
centrated fertilizers may produce death to the plant,
and it may be by this action. Applying the principle
to the alkalies in the soil, it must be recalled that
these compounds are all relatively very soluble in
water, so that if only large quantities of water con-
taining even small amounts of the salts are evaporated
in contact with the roots of growing crops, the so-
lution surrounding the soil grains may become too
strong for good plant feeding, and even death may
result.
On this fundamental principle of action, it is plain
that the black as well as the white alkalies fall into
the same category, and this, too, no matter what may
be their composition, origin or geographic range.
It is more than probable, if not even certain,
that the action of some of these salts may be that of
true poison ; but the real nature of toxic effects is not
as yet understood in any full sense.
272 Irrigation and Drainage
HOW ALKALIES ACCUMULATE IN THE SOIL
Everywhere in the soil where there are sufficient
changes in the air and the moisture, the soil grains
are being broken down and dissolved by both physical
and chemical means, and unless the rains are suffi-
ciently heavy to carry the ever -forming dissolved
salts away in the country drainage, they will be
brought to the surface by capillarity and there con-
centrated until precipitated. The more insoluble of
the plant-foods, and other salts which are not such,
cannot charge the water sufficiently high to do serious
harm, hence in common language and in the sense
the term is here used, they do not become "alkalies."
But with the other salts the case is different.
They are precipitated when the solution becomes
strong enough, and form deposits on the surface or
about the roots in the soil where water is being re-
moved, but before this actually occurs one or both of
the actions referred to above begins to take place.
In arid regions, where the alkalies proper are most
abundant, rains enough may fall to slowly carry for-
ward theu" formation, but not enough to carry them
out of the land. From the higher levels and steeper
slopes thej^ are readily moved by surface drainage and
wind action to the lower lands, where the amount
may become so large as to form thick beds. During
the wet season of such countries, these salts may sink
into the soil, but to rise again when dry weather
restores the action of capillarity.
In the humid regions, there is necessarily an even
How Alkalies Acctnnulate in Soil 273
more rapid formation of all the true alkalies of arid
climates; for fundamentally similar rook ingredients
are subjected to identical weathering processes, but of
a more intense nature, because the rainfall is greater.
If, therefore, there occur conditions favorable to the
accumulation of the soluble salts formed at and near
the surface of the soil, these should be expected to
show as alkalies.
Most of the marsh lauds of the world, excepting
those under the influence of tide waters, owe their
wet character to the underflow of ground-water which
has percolated into the adjacent higher lauds, and
which rises to or near the surface wherever this is
sufficiently low to permit of it doing so. When such
lauds are drained, the rate of surface evaporation and
the rise of capillary water from below^ may exceed
the annual rainfall, and thus lead to an accumulation
at the surface of salts of such intensity and character
as to interfere with the normal growth of plants.
It must be kept in mind that where the ground- water
level is near the surface, the rate of capillary rise may
many times exceed what it could be under other con-
ditions, and since the rate of evaporation is most
rapid where the surface soil is wettest, the conditions
are extremely favorable for the accumulation of solu-
ble salts at the surface of marsh lands in humid
climates after they have been dr lined. The waters
leaching through the more open, higher lands become
charged with salts, and as these waters come again
near the surface under the low areas thej' are raised
by capillarity and evaporated, leaving the salts which
274 Irrigation and Drainage
had been taken np along the underground path
to accumulate over the low -lying lands, and since
the evaporation of 12 inches of salt -laden water may
produce more deposits than the same depth of rain
would be sure to remove in leaching downward, the
chances are favorable to accumulation.
INTENSIVE FARMING MAY TEND TO THE ACCUMU-
LATION OF ALKALIES
It has already been pointed out that during the
growing season, after vegetation has come into full
action, nearly all of the rains which fall in humid
climates are retained near the surface until they are
evaporated, either through the growing crop or from
the soil, and since these waters tend to form salts
when they are in contact with the soil grains, they
must tend to increase the salt content near the surface.
It is plain, too, that the heavier the crops produced
aud the greater the number of them iu the season, the
less is likely to be the loss of any water fro:n the field
by under- drainage ; hence the greater the tendency
for solul)le salts to accumulate. Then, if during the
winter season of a country the rainfall is deficient, so
that little leaching can take place, conditions become
still more favorable for the accuuuilation of alkalies.
Further thau this, if irrigation is practiced during
the growing season only, aud this water also is
evaporated from the soil in addition to the natural
rainfall, it is plain that the amount of soluble salts
in the soil must increase, both on account of that
which may have been in the water applied, and that
Amount oj Alkali Injurious 275
which this additional water may have been instrumental
in producing from the soil on the spot through the
processes of weathering.
Indeed, the more we study and reflect upon this
problem, the more we are led to fear that in all arid
climates, where irrigation is practiced, it will not be
found sufficient to apply simply enough water to the
soil to meet the needs of the crop growing upon the
ground at the time, but, on the contrary, there must
be enough more water applied to take up and carry
away into drainage channels and out of the country
to the sea not only the soluble salts which the irriga-
tion waters carry, but also those which it causes to be
produced from the soil and subsoil. In other words,
it appears that an excess of soluble salts in a thoroughly
irrigated field is not only a normal but an inevitable
condition, unless sufficient leaching takes place; and
if this is true, the sparing use of water can only
increase the number of years required to bring the
salts up to the danger point of concentration.
AMOUNT OF SOLUBLE SALTS WHICH ARE INJURIOUS
IN SOILS
Storer states that it is a matter of record that long
experience in the south of France has shown that any
soil which becomes visibly covered with a slight in-
crusation of salt in times of drought is improper for
cultivation, unless special pains are taken to prevent
the surface from becoming dry.
Plagniol insisted, in his time, that soils containing
more than 2 per cent of salt are unfit for the growth
276 Irrigation and Drainage
of aDv other than samphire, saltwort, and the like,
and that even these cannot thrive when the salt
becomes as high as 5 per cent.
Deherain concludes, from his studies in France,
that while soils kept very moist may produce crops
even when 2 per cent of salt is present, yet if the
soils dry out badly they become sterile with no more
than 1 per cent present. Gasparin has maintained,
however, that while soils containing .02 per cent of
salt may produce good crops of wheat, .2 per cent
is more than this crop can bear.
Speaking, next, of the alkali salts of arid climates,
we may cite some of the data procured by Hilgard in
his extended and careful studies of the alkali problems
of California. At their Tulare Experiment Station,
he gives both the amount and the distribution of
soluble salts in the surface 18 inches of soil where,
in one case, barley grew to a height of •! feet, and in
another the amonuts of the salt were so great that
this crop would not thrive. The data which we give
in tabular form have bef^n read from his plotted' curves,
hence the values must be regarded as not quite exact.
Table shoicing amount and composition of allcaH salts in parts per 100
Taken September, 1894. Tulare Experiment Station, California
Depth in
3-in
sections
Ground npon which barley
grew 4 feet high
Sodium Sodium Com'n Total
carb'ate .sulphate salt soluble
NaoCO, NaoS04 XaCl ^'^^^
Ground tipon which barley
did not grow
Sodium Sodiiim Com'n Total
carbato sulphate salt soluble
Na.COa Xa.SOi NaCl «"'**
to 3 in.
.. .008
.68
..36
1.2
.07
1.22
.68
2.44
3 to 6 in.
.. .009
.26
.07
.34
.1
.16
.1
.38
6 to 9 in.
. . .013
.1
.03
.168
.099
.11
.05
.28
9 to 12 in.
. . .024
.057
.02
.143
.090
.US
.06
.334
12 to 15 in.
.. .038
.037
.02
.119
.14
.1
.04
.29
15 to 18 in.
.. .04
.02
.02
.09
.18
.06
.02
.263
Amount of Alkali Injurious
277
Sodium nitrate is also given in these cases as a
constituent, but as this may be regarded as a jilant-
t'ood, we have omitted it from the table. It will be
observed that the total soluble salts in the surface 3
inches where the barley grew well was about half that
found in the case where it would not grow, the amounts
in the two cases being 1.2 and 2.44 per cent of the soil.
The difference between the amounts of the black alkali
in the two cases stands as 8 to 70, or much more.
Referring to the possibility of these salts interfering
with plant life simplj' on account of their plasmolitic
action, it may be said that DeVries found, as repre-
sented in Fig. 49, that when the living cells of a plant
were immersed in a 4 per cent solution of potassium
Fig. 49.
Effect of too strong solution of potassium nitrate on the
protoplasm of plant cells. (After DeVries.)
nitrate, there was first a shrinkage in volume through
a loss of water, as shown between 1 and 2. When
the solution was given a strength of 6 per cent, then,
in addition to the change in volume, the protoplasmic
lining P began to shrink away from the cell wall h.
as shown at 3, and when the strength of the solution
was made 10 per cent, the conditions shown in 4 were
278 Irrigation and Drainage
produced. When such conditions as those represented
in 3 and 4 are set up, marked wilting must result and
growth be brought nearly or quite to a standstill.
It is not possible to state with certainty what
strength of salt solution existed in the soil moisture in
the cases cited above, but an approximate estimate
may be made. Hilgard's analyses show, in the case
of the sample from where barley would not grow,
that the soluble alkalies amounted to 2.44 pounds per
100 pounds of soil. It' these salts were all in solution
in the soil -water, and if the soil -water amounted to
30 per cent of the dry weight of the soil, then the
salts in solution would have a strength of 8.13 per
cent. But if only 15 per cent of moisture existed in
the soil, as might easily have been the case, and all
the salts were in solution, then its strength would
have been double that above, and much stronger than
DeVries' most severe trial. It does not appear im-
probable, therefore, that even were there no poisonous
effect exerted upon the barley by the salts in the soil,
the plants could not have grown, on account of the wilt-
ing which would have resulted from the presence of
too strong a salt solution outside the cell walls of the
root -hairs in the soil.
COMPOSITION OF ALKALI SALTS
To show the character of the salts which accumu-
late in the manner under consideration, we have
computed the mean composition from a number of
analyses as given by Hilgard, and the results are
stated in the table which follows :
Composition of Alkali Salts 279
Tabh .ihnu'ing comiiosition of alkali salts
Acids and bases California Washington Montana
Silica (SiOa) 1.663 1.552 .42
Potash (KoO) 3.602 9.588 1.774
SodalNaoO) ' 40.058 45.387 30.442
Lime(CaO). 519 .048 lAbt
Magnesia (MgO) .258 .115 5.956
Peroxide of iron (FejOi)) :i:i I alu-
mina f AI2O3) 079 .028 .04
Phosphoric acid (P2O5) 1.457 .81 .012
Sulphuric acid (SO3) .. 18.946 2.12 44.482
Nitric acid (N0O5) 1.923 .000 1.074
Carbonic acid (CO2)... 13.982 34.058 2.208
Chlorine (CI) 7.46 1.077 5.148
Ammonia (NHs) 047 .000 .000
Organic matter and water of crystalli-
zation 11.282 5.073 8.136
101.276 99.856 101.156
Less excess of oxvgen corresponding
to CI ". 1.623 .238 1.166
Totals 99.653 99.618 99.990
When these results are computed as salts they
stand, according to Hilgard, as expressed below:
Table showing composition of soluble portions of alkali salts
California Washington Montana
Potassium Sulphate (K2SO4) 6.796 3.715 3.774
carbonate (KoCCi) 732 12.378 .000
Sodium sulphate (NajSOj) 31.956 .000 61.432
" nitrate (NaNO^) 3.64 .000 1.878
carbonate (Na2C0:,) 39.413 80.053 2.94
chloride (NaCl) 14.703 1.913 9.864
" phosphate (HNaaPOi) 2.273 1.943 .000
Magnesium sulphate (MgS04) 307 .000 21 .12
Ammonium carbonate (NH42CO3)... .157 ■ .000 .000
280 Irriijidwu atid Drainagf
It will be seeu from these two tables that there
may be associated with the undesirable salts quite
notable quantities of others which are valuable plant-
foods. This is as should be expected, for the more
soluble plant-foods, as well as the salts not suitable
for plant life, must be moved bj' the same waters,
and tend to collect with them.
Hilgard points out that where the soluble phos-
phates and considerable quantities of humus are asso-
ciated with the sodium carbonate or black alkali, it is
often desirable to first transform the sodium carbo-
nate into sodium sulphate through an application of
land plaster. By so doing both the humus and
phosphates are rendered insoluble, but not unavaila-
ble for plant -food, hence may be retained in the soil
for future use after the alkalies, which are harmful,
have been washed out or otherwise disposed of. This
is an important suggestion to keep in mind.
THE APPEARANCE OF VEGETATION ON
ALKALI LANDS
When cultivated crops are grown upon alkali lands,
characteristic effects are produced which serve to point
out the difficulty Avith the soil and the remedy which
should be applied. If the salts in the soil are not too
concentrated, the crop maj' germinate in a perfectly
normal manner, but after a time begin to languish in
spots, and remain dwarfed in stature or entirely die
out. It is very common to see a field upon which the
crops present an extremely uneven stand, some areas
Aiipearnnce of Vcf/efation on Alkali Lands 281
being entirel}' destitute of plants, or bearing onlj^ those
which are small, while closely adjacent spots may be
covered with large, vigorous, and perfectl}' normal
growths. Fig. 50 illustrates this feature, as it is ex-
hibited in the San Joaquin valley of California, and
Fig. 51 shows essentially similar features as they de-
velop on black marsh soils in Wisconsin after thej' have
been tile -drained. In this latter case, the crop on the
afflicted areas comes to an early standstill, or a plant
Fig. 50. Vegetation on alkali lauds in California. (Hilgard.)
may go through all the phases of growth, reaching
maturity, but with a very dwarf habit, so that maize
in tassel and ear may not stand higher than 6 to 10
inches, while close by may stand another hill or group
of them where the growth has been unusually rank
and luxuriant. On these soils the afflicted plants pos-
sess a very imperfect root system, the older roots
turning brown, soft, and apparently decaying, while
new ones form above.
282
Irrigation and Drainage
DISTRIBUTION OF ALKALIES IN THE SOIL
The position in the soil where the alkalies may be
found in greatest abundance varies under different eon-
Fig. ")!. Growth of maize on W;;i-k marsh soil in Wisconsin.
ditions. Where there is a large and prolonged evapo-
ration at the surface, the alkalies may be nearly all
collected within the surface 3 or 4 inches, and hence be-
come so strong as to do serious injury, when if this
Disfrihufion of All-ali in Soil 283
concentration luid been prevented no serious harm
could have resulted. So, too, if the salts have been
gathered into a thin layer near the surface, heavy
rains or an application of water by irrigation may
move them at once bodily and nearly completely to a
depth of 1, 2 or 3 feet, varying with the amount of
water applied, the capacity of the soil to store water,
and the amount of water it contained previous to the
application. Under these circumstances, it is plain
that fields afflicted with alkalies may exhibit at one
time the most intense symptoms of poisoning and at
another be entirely free from them, so far as revealed
by a crop upon the ground.
In examining soils for alkalies, it is a matter of
the utmost importance to recognize that the distribu-
tion of them is extremely liable to be Ccipricious, and
that it is easy to overlook their presence by stopping
the sampling of the soil just short of the level at
which all of the alkalies had chanced to be concen-
trated ; or, again, by taking a sample of the 1st, 2d
and 4th feet, or of the 1st, 3d and 4th feet when, ow-
ing to the capricious distribution, all of the salts had
been collected in the 2d or 3d foot, and thus were
overlooked because it may have been thought not
worth w^hile to make a complete section of the soil
in question.
CONDITIONS WHICH MODIFY THE DISTRIBUTION
OP ALKALIES IN SOIL
If the surface of the ground is kept naked and
compact, so that the rate of evaporation may be
284 Irrigation and Drainage
strong, the alkalies will ueeessarilj' be broug-lit to the
surface and become concentrated there, hence in posi-
tion to do the greatest harm to growing crops.
If thorough tillage is practiced early, so that but
little water is evaporated except that which passes
through the roots of the crop, then the salts cannot
become concentrated in a narrow zone, but, on the
contraiy, will be left all through the soil where the
roots which are taking water are distributed. lu those
cases, therefore, where the general soil water is not
too highly concentrated to permit normal growth,
crops may prosper so long as the surface is kept
shaded and thoroughly tilled.
It must be observed, however, and kept in mind,
that the roots of plants caunot withdraw moisture from
a soil without at the same time tending to concentrate
the salts in solution iu the zone where the roots do
their feeding ; hence, that if alkali Avaters are being
used for irrigation, and in the long run if the purest
waters are being used uuder conditions of no drainage,
sooner or later the soil of the root zone must become
so highly charged with the alkali salts that reduced
yields are inevitable.
USE OF LAND PLASTER TO DESTROY BLACK ALKALI
Hilgard long since pointed out that iu regions
where the water contained sulphate of lime in solu-
tion, there sodium carljonate was absent, or existed in
such small quantities as not to be harmful to crops, and
he earlj-. saw and recommended that where fields were
Land Fluster for Black Alkali 285
troubled with black alkali iu not too large quantities,
land plaster could be used as a fertilizer, which would
have the effect of changing the sodium carbonate into
the less harmful sodium sulphate, and in this way
transform sterile lands into those which are capable
of being worked at a profit. He clearly saw, however,
that such a remedy was not an absolute corrective,
but rather of the nature of a substitution of a lesser
for a greater evil, as, sooner or later, the sodium sul-
phate comes to be too strong to be endured.
Hilgard has further pointed out that the application
of land plaster to a soil rich in sodium carbonate very
greatly improves the texture or mechanical condition
of such a soil, because black alkali tends to break
down the granular structure of clay soils, and thus
puddles them and renders them nearly uninhabitable
by most plants, largely on account of their bad
mechanical condition.
Still further has Hilgard pointed out that the pres-
ence of black alkali in a soil -water tends to dissolve
the humic nitrogen and the comparatively insoluble
phosphates of the soil, so that if leaching is taking
place under the influence of a water containing much
sodium carbonate, great harm is being done by depriv-
ing the soil of two of its most important ingredients
of plant -food. Hence if alkali lands are to be im-
proved by drainage, this should not be done until
steps have .been taken to first transform the sodium
carbonate to the sulphate, and thus precipitate the
humic nitrogen and the phosphate so that these may
be retained.
286 Irrigation and Drainage
KINDS OF SOIL WHICH SOONEST DEVELOP ALKALI
Where alkali waters are used for purposes of irri-
gation, and where sweet waters are being used under
conditions of little or no drainage, the clayey soils
are the ones which soonest begin to show the bad
effects of concentrated salts. This is so for many
reasons.
In the first place, the soils of clayey texture, as has
been established b}^ experiments recorded on page 201,
are not as effective mulches as the sandy soils, hence,
even where thorough tillage and shade are resorted
to, there must necessarily be a larger rise of salt-
bearing water to the surface to produce accumulation
than is the case with the coarse, sandy soils.
In the second place, when water is applied to a
sandy soil, not nearly as much remains adhering to
the surface of the soil grains and entangled between
them, so that it quickly spreads downward farther
below the surface than is the case with the clay. This
being true, it takes less water to produce effective
drainage, and the roots of the crop spreading farther
in the sands, the salts cannot become concentrated as
they may in the clays.
In the third place, since more water is held in
contact with the soil grains of the clays, and since
the total surface for chemical action to take place upon
is very much larger in the clayej^ soils than in the
sands, it is plain that soluble salts, including alkalies,
may form more ra])idly in one ease than in the other,
and hence, that the open, sandy soils cannot become
Correction of AUali ^Y(lters 287
alkali lands except under couditious which are ex-
tremely favorable to their forinatiou.
CORRECTION OF ALKALI WATERS BEFORE USE IN
IRRIGATION
In case an irrigation water is known to contain an
injurious amount of black alkali, it is possible to con-
vert this into the sodium sulphate by the use of land
plaster in the water before applying- it to the field.
To do this in the cases where water is stored in
reservoirs, it is possible to arrange cribs of uncrushed
gypsum through which the water flows in entering the
reservoii', and if this should not be sufficient to effect
the whole change, other cribs could be built at other
points in the reservoir and at the outlet. 80, too,
where the lateral is taken to the field, it would often
not be difficult to arrange so that the water flowed
through a basin, wide ditch or reservoir in which hang
crates of gypsum, over which the water passes on its
way to the field, or the same method maj- be applied
in the larger cauals.
If the fields upon which alkali waters must be used
are heavy and especially likely to be injured by the
puddling process, it would seem to be much the better
method to apply the corrective for black alkali to the
water itself, rather than to the field, after there has
been opportunity for some damage to be done.
DRAINAGE THE ULTIMATE REMEDY FOR ALKALI LANDS
If it is true that alkali salts are formed from the
decomposition of the soil and subsoil through the ac-
288 Irrigation and Drainage
tiou of water and air, it is only too plain that where
conditions are persistently maintaiued which allow the
formation of the salts without permitting them to be
removed bj- any cause whatsoever, there must come a
time, sooner or later, when the amounts produced and
accumulated in the soil shall reach the degree of con-
centration which is intolerable to cultivated crops.
Under the natural conditions of rainy countries, there
is usually a sufficient amount of leaching to permit
the white and black alkalies to be borne awaj^ in the
country drainage with sufficient completeness to pre-
vent their effects attracting general attention, and if
the same processes obtained in irrigated countries, it
is plain that in these, too, the difficulties would not
arise. The conclusion is irresistible, therefore, that some
method must be devised by which, periodically at least,
sufficient water is applied to irrigated fields to pick up
and carrj" out of the country- the soluble alkali salts
which are fatal to cultivated crops.
In the old-time irrigation of tb.e Nile valley, the
greater part of the land was under basin irrigation,
and thus thoroughly washed during some fifty daj'S
every year. Lands not so treated were the lighter
sandy soils near the Nile, protected by only slight
banks from inundation, and these dykes usually gave
way as often as every seven or eight years, so that
they, too, were occasionally thoroughly flooded. Un-
der this system of washing and drainage, the fields of
the Nile were kept free from alkalies for thousands of
years. But at the present time, when what are called
more rational methods are being applied, but with no
Drainage the lUt'unate Eemedij for Alkali 289
attention being paid to freeing the soil from the ac-
cumuhition of alkalies, these salts have been concen-
trated to so serious an extent that already many acres
have been abandoned.
The probabilities are that long, long ago the same
more rational methods (?) now being practiced had
been tried and found inadequate or inapplicable, on
account of the accumulation of alkalies which they
permitted, and the old irrigators learned to be content
with a system which, although more wasteful in some
ways, still kept the dreaded alkalies under control.
It is not improbable that if the full history of
many abandoned ancient irrigation systems could be
known, it would be found that, not being able to
command water sufficient for drainage, or not appreci-
ating its need, alkalies were allowed to accumulate
until the lands were no longer productive.
It is a noteworthy fact that the excessive develop-
ment of alkalies in India, as well as in Egypt and
California, are the results of irrigation practices
modern in their origin and modes, and instituted by
people lacking in the traditions of the ancient irri-
gators, who had worked these same lands for thousands
of years before. The alkali lands of today, in their
intense form, are of modern origin, due to practices
which are evidently inadmissible, and which, in all
probability, were known to be so by the people whom
our modern civilization lias supplanted.
The subject of Drainage will be discussed in
Part II.
CHAPTER IX
SUPPLY i:Na WATER FOB lEBIGATION
It is not the purpose iu this chapter, nor has it
been the purpose in this work, to discuss the larger
questions of water supply for irrigation. These are
quite purely engineering problems, involving a mass
of detail and technicalitj- which concern the agricul-
turist only in the final results which they bring to
him ; hence, he is interested in them only iu a
general way.
We shall aim, therefore, in dealing with the supply
of water to whole communities for purposes of irri-
gation, to present only a general idea of the systems
which have been evolved and adopted under the
varying conditions of different countries and climates,
reserving the main part of the chapter for the dis-
cussion in detail of the cases where water is supplied
by individual effort for individual use.
DIVERTING RIVER WATERS
By far the most general method of supplying water for the
use of large sections of country is to throw a dam aei'oss a stream,
and divert from the channel a portion of the river water,
leading it out into the district to be watered through canals
provided for the purpose.
(290)
Diverting Water from Streams
291
An excellent example of such a large scale sj'stem is i-ei^re-
sented in Fig. 52, which shows the Sirhind canal, taken out of
the Sutlej river, in the Punjab of India, at Eupar. This canal
was designed to have a carrying capacity of 6,000 cubic feet
per second, and extends as a single main trunk 41 miles, where
it is bisected. Three miles further on the western trunk it is
divided again, forming two canals of 100 and 125 miles respec-
tively, while the eastern main branch divides into three of 90, 56
Sirhind canal system, Punjab, India.
(Wilson, U. S. Geol. Survey.)
and 25 miles respectively. There are in the whole system 41 miles
of main canal, 503 miles of main branches, and 4,407 miles of
main distributaries, supplying 800,000 acres of irrigable lands.
The annual rainfall of the region in which this system has
been developed varies from 10 to 35 inches. The sytem is said
to have cost $7,831,000, and to have yielded in 1899 an annual
revenue of 2%^ per cent on the cost, although less than half -of
the available land has yet been brought to use the water.
We have already referred to the head gates of one of the
292
Irrigatioti and Drainaye
cauals of the Durance, and given an engraving of it in Fig. 48.
In furtlier illustration of the methods used in diverting by gravity
the water of a stream for purposes of irrigation, Fig. 53 shows
diagram matically how the Kern Island canal, in California, is
taken from the Kern river, together with the position of the
regulator, and of the waste gate by which the unused water finds
Pig. 53. Head of Kern Island canal, California.
(Gninsky, U. S. Geol. Survey.)
its way back into the channel. Figs. 54 and 55 are bird's-eye
views of the same thing, showing the regulator and the waste gate.
In Fig. 56 is given a nearer view, looking across the canal over
the waste gate, the regulator being at the left.
In aligning these canals, they are led back from the stream
as far as the general fall of the valley will permit, and in taking
out the laterals and distributaries, these are carried to the highest
portions of the fields to be irrigated, and at the same time are
Divfrting Wafer from Streams
293
held as far as possible above the level of the surface, in order
that there shall be no difficulty in taking out the water upon the
land to which it is to be applied.
If reference is again made to Fig. 52, it will be easy to
Fig. 54. Bird's-eye view of head of Kern Island canal, looking up stream.
(Grnnsky, U. S. Geol. Survey.)
understand that where such vast volumes of water are taken
across a country in open canals, carried as high as possible and
even above the surface, there must necessarily be an extensive
seepage into the subsoil, which in the course of time must
tend to raise the original ground-water level much nearer the
294
Irrigation and Drainage
surface, and tend to develop swamps in the lowest- lying and
flattest sections of the area traversed.
It is further clear, too, that under the conditions set up by
such a network of canals, there must be a much more rapid
^^m^-:Mm^. - i
Ik
■ X ' 1
Fis
Wk'-m\ or K.-ni M;hm1 r:ni:il, i-.'/kM.u
(Gi-uusky, U. S. Geol. Suivey.)
action of water upon the subsoil to form alkalies ; and since,
with the nearer approach of the ground water to the surface, the
capillary action and evaporation must be much augmented, it
is plain that the deterioration of land through the increase of
alkalies is the thing to be feared rather than wondered at.
Divertwg Water from Streams
295
In laying out such a system of irrigation as the one under
consideration, it thus becomes a matter of the greatest moment
that proper attention be paid to drainage, and that ample pro-
vision be made for it. If this is not done, a relatively few
Fig. 50. Waste gate and regulator at head of Kern Island canal, looking across
the canal. (Grunsky, U. S. Geol. Survey.)
years are almost certain to convert a great benefit into one of
the most serious of scourges. Drinking waters are likely to
become polluted, malarial fevers prevalent, and the land unpro-
ductive, both on account of water-logging and the excessive
accumulation of alkalies.
296 Irrigation and Drainage
The dangers in this direction will be least in countries where
the natural drainage facilities are best ; where the streams, draws
and washes are sunk deepest below the surface of the fields;
and where the subsoil is the most open, thus providing an easy
escape of the seepage waters into the natural drainage channels.
Under such conditions as these, it would be only the most waste-
ful, extravagant and inexcusable use of water, with no attention
to proper methods of tillage, wliich could lead to the evils
pointed out.
But, on the other hand, in countries where the natural
drainage lines are shallow and few, and where the soil and
subsoil are close, it will require the greatest vigilance and the
rarest skill and judgment to avert the evils of swamping, the
.development of a malarial atmosphere, and the formation of
alkalies. If, in atldition to the conditions last pointed out, the
irrigation water is naturally heavily charged with undesirable
salts, then the situation becomes as serious as possible.
"When capital, therefore, is seeking permanent investment
in the development of an irrigation system, the difficulties
pointed out are matters for first and most serious consideration;
and when agriculturists propose to establish homes under such
surroundings, the same serious attention should be given the
probable permanency of the conditions of fruitfulness and health-
fulness.
It sometimes happens that water for irrigation must be taken
from mountain canons and led out upon the mesas and over the
valleys under great difficulties, such as tax the highest engi-
neering skill to its utmost to accomplish. As an illustration of
this type of irrigation engineering, the case of one of the canals
supplying Redlands, California, may be cited. In Fig. 57 the
dai-k line on tlie flank of the mountain on the right is an open
canal, with cement masonry lining, which winds up the valley
until it can draw its supply from the Santa Ana river. Lower
down the mountain valley it becomes necessary to cross the canon,
and this is accomplished by using the large redwood siphon rep-
resented in Figs. 58 and 59. This gigantic pipe has an inside
diameter of 4 feet, and in one portion of its course is obliged
Redlands Irrif/dfion Sijstevi
297
to withstand a pressure of 160 feet of water. This pipe is made
of selected redwood staves, 2x6 inches, with edges beveled to fit
closely, and having their ends joined by a strip of metal fitting
tightly into a slot in the end of each stave ; the width of the
metal strip being a little greater than the width of the stave,
Fig. 57. Santa Ana canal on mountain side.
a close joint is thus secured. The staves are bound together
with iron hooi^s, whose distance apart is varied according to the
pressure the pipe is required to withstand.
When the canal reaches the wash of Mill creek, it is carried
across in the flume represented in Fig. 60, also made of redwood
staves. Further on, as the water nears its destination, one
branch discharges its water through the paved and cement- lined
canal into the paved and cement-lined distributing reservoir,
both shown in Fig. 61.
From the reservoir, the water is taken in a system of under-
Fig. 58. Redwood pipe r-oiiveyiiig water of Santa Ana canal
into aud out of a eaiiou.
Redwood Pipe Line 299
ground cement pipes to the lands where it is to be used. These
pipes extend beneath the surface, out of sight and out of the
way, ranging from 14, 12, 10 and 8 inches in diameter for the
mains, to 6 and 5 inches for the laterals ; and there were in
1888 some 13 miles of these pipes in the Eedlands settlement.
In the general system, the lands are plotted in square
10-aere lots, and a 5- or 6-ineh lateral supplies one tier of these,
delivering the water usually at the highest corner. These pipes
Fig. 59. Pipe line c;iri-ieil on ti-estle.
are generally laid on the slope of the country, which one way
ranges from 50 to 100 feet per mile, and do not carry the water
under much pressure, but rather more nearly as though it were
running in open channels. The accumulation of pressure as the
face of the country falls is prevented by the introduction of
small concrete chambers from 5 to 6 feet square, placed at
frequent intervals, and at the places of branching. As the water
passes along the supply pipes it enters these chambers, rising
until it falls over measuring weirs in the partition walls of the
chamber, and drops into other compartments from which other
pipes lead away in their respective directions.
Krdwood stave flume earrieci r.?ross Mill ereek wash on trestle.
Fig. 61. Cement -lined canal and reier^-oi^ at Redlands, Lamuiuui.
Distrihufing Hydrants
301
When the water reaches the irrigator, his delivery is made
over a small weir, to which the water rises from below in a
similar but smaller cement chamber, two of which are repre-
sented in Figs. 62, 63 and 64. In Fig. 62, the water is seen
pouring from the cement chamber or " hydrant " over a small weir
into a distributing flume. Two other weirs in the same hydrant
are closed by gates, and it will be seen that by transferring
either of the two gates to the weir now in use, the water would
Fig. 62. Oement hydrant, with weir and distributing tlume.
be turned from its present course to the one of the other two
desired. In Fig. 63, the water is seen" flowing from the front
weir, while the discharge is prevented from taking place into
the compartment at the left and in the rear by the two gates
now in place ; but i;i Fig. 64, the left gate has been removed
without putting it i;i front, as would oidinarily be the case, so
as to show the water pouring over that weir into its underground
pipe for delivery in another direction.
The system for supplying water for irrigation, now briefly
described, and illustrated by Figs. 57 to 64, represents the high-
302
Irrigation and Drainage
est type of collecting and distributing systems j^et devised, and
it is one which meets the peculiar demands brought upon it with
almost ideal nicety. From the collecting reservoir, up in the
mountains, behind the great Bear valley dam, the water travels
Fig. 63. Cement hydrant, with water discharging outward
into distributing flume.
hurriedly much of the way through closed pipes of redwood,
steel or cement, in which all evaporation and seepage are effec-
tually prevented, while for most of the balance of the distance
the water glides swiftly along tight flumes and cement-lined
Pig. 64. Same hydrant as Fig. 63, with water discharging
over left wier into Tindergrouud pipe.
canals of nearly faultless alignment, reaching its destination with
so little of erosion or silting that the annual expense for mainte-
nance is almost a trifling matter. The dangers from alkalies are
reduced to the narrowest possible margin, and the swamping of
304 Irrifjation and Brmnaye
the land is next to impossible with any rational use of water.
When one stands upon Smiley Heights, in Kedlands, and looks
out over such panoramas of luxuriant growth as the one repre-
sented in Fig. 65, the reflective mind is almost convinced that
here is in reality the ultima thide in rural life.
The cases now cited may suffice to illustrate the manner in
which water is diverted from streams for gigantic irrigation
enterprises, where the government itself does the work, as in
India ; where state aid supplements the united efforts of a dis-
trict, as in the case of the Kern river canal, and where one or
more stock companies develop the system as a means of finding
permanent investment for capital, as is the case with the system
worked out to meet the needs of the Eedlands district.
It is, of course, practicable for individuals to divert portions
of the water from streams passing- through their property, pro-
vided the fall is such as to permit of this being done, and
where large quantities of water are to be used there is seldom a
cheaper Or more effective method of supplying water, if only
the land and the stream are proper!}^ related for it, and the
water is not already held by prior rights.
diverti^;g underground waters
In mountainous and hilly countries, where river valleys have
become deeph' filled with sands and gravels, it frequently happens
that much of the water of the drainage basin flows below the
surface through the valley sands and gravels, the bed of the'
channel becoming nearly or quite dry for long distances.
In such cases, where the slope of the valley is considerable,
and where the water has not fallen too far below the surface,
tunnels are occasionally driven into the sands and gravels up
the valley at a small grade until the water-bearing beds have
risen 'above the line of drift sufficiently to allow the water to
percolate into the tunnel and be led out upon the surface.
Sometimes it is only necessary to dig open ditches, making them
deeper up stream, to develop considerable quantities of water on
the same principle.
Diverting Underground Waters
305
Then, again, in steep valleys, where the streams carry plenty
of water, but too far below the surface to be diverted, it fre-
quently happens that at the foot of a terrace water may be
flowing very near the surface toward the river channel, and by
ditching or tunneling here this may be diverted to the surface
when that in the river must be pumped.
Another method of utilizing the waters which have fallen
below the surface in the valley gravels is by building what is
called a submerged dam across the valley, excavating to bed
Fi;;. Uti. Submerged dam at San Fernando, California.
rock and erecting a water-tight dam, which shall hold the under-
flow back until it has filled the gravels above the dam and flows
over it at the surface high enough to be taken away in cement
ditches, flumes or pipes to the land it is desired to irrigate.
One such submerged dam is shown in Fig. 66, built neai* San
Fernando, California. It was not, however, sufliciently well built
to hold the water back until it could be made, to overflow, and
they were, in 1896, using two gasoline engines with pumps to
lift the water held back by the dam, instead of depending upon
gravity, as planned.
306 Irrigation and Drainage
DIVERTING WATER BY TIDAL DAMMING
Where lands borderiug rivers leading to the sea lie high
enough above low tide to admit of adequate drainage, and at the
same time below high tide level, these may be dyked off from
the- sea, and then, by erecting sluices controlled by gates at
suitable places in the dykes, connecting with canals and dis-
tributaries on the land side, water may be led at will on or off
the fields as the tides come or go. One of the most notable
examples of this method of procuring water for irrigation is
at the mouth of the Santee river, in South Carolina, to which
refei'enee has already been made, and a portion of which is
represented in Fig. 67.
It will be readily understood that as the tide rises along the
coast, the discharge of the fresh water coming down the river is
prevented and the channels fill with it, it being held there by
the dam of salt water formed by the tidal wave. When the
fresh water has accumulated to a sufficient extent, the trunks
may be opened and the fields flooded,' or they may be kept
closed and the water held off. The diverting of water from
rivers by tidal damming is only practicable where the river
carries a sufficient volume of fresh water to prevent the salt
water from ascending the channel, for were the volume small
the sea would drive it back, and only salt or brackish water
would be found against the dykes.
DIVERTING WATER BY THE POWER OP THE
STREAM
Where rivers run too low in their channels to permit
the water being led out directly, many devices have been
employed by which a portion of the water is made to drive
machinery which, in turn, lifts another portion out upon the
land, where it may be led away. One of the oldest, commonest
and simplest devices used for this purpose is the undershot
water-wheel, set up in the stream and carrying buckets on its
Tidal Irrigation
307
BORMAY It CO.,ENGR'
Fig. 67. Section of rice fields in Soiitli Carolina.
(U. S. Coast and Geodetic Survey.)
cireumfereaee, which raise the water in the manner represented
in Fig. 15, page 76. This view was taken on the river Eegnitz,
a branch of the Main, in Bavaria, where in a distance of one
308
Irrigation and Drainage
and one-fourth miles the writer counted no less than twenty
such wheels.
The wheels were 16 feet in diameter, provided with a row
of 24 ehurnlike buckets on one or both sides, emptying their
contents into a trough, from which the water was led away in
a flume hewn from a log. At the time the view was taken,
this wheel was making three revolutions per minute, and dis-
charging 450 gallons, or enough to supply nearly 120 acres witli
2 inches of water every 10 days, the water being raised 12 feet.
On the Grand river, near Grand Junction, Colorado, the
Smith Brothers have placed two 36-inch turbine wheels so
that they drive a battery of two centrifugal pumps, one above
the other, on the same 8-inch discharge pipe, and lift water
82 feet, discharging it into a flume, as represented in Fig. 68,
I'iji. OS. MduTli of s-iiich disi-li.'irj^o pipe 81; feet above Grand river,
Grand Junction, Colorado.
at the rate of 2,200 gallons per minute. The two wheels were
together rated at 90 horse-power, and were developing not far
from 54, as measured by the water lifted. They were supply-
ing water for 80 acres of alfalfa and 120 acres of orchards,
working only during the daytime, the water being carried a
mile in flume and ditches.
Other forms of water wheels, like the overshot, undershot
and breast wheels, are used for driving centrifugal and other
pumps to lift water for irrigation, and in large streams, where
Lifting Water hy Water Power
309
there is considerable fall, large amouuts of water may be
raised at a very small cost after the plant is once in place.
Mr. F. H. Harvey, of Douglas, Wyoming, has set up a half-
breast and undershot wheel, 10 feet in diameter and 14 feet
long, between two wing-dams on a swinging frame, in such a
manner as to permit it to rise and fall with the current. Being
connected by means of a sprocket wheel and chain to the sta-
tionary driving pulley, the changes in the position of the wheel
with the level or the river do not disturb the action, and the
Fig. 69. Hydraulic ramming engine. (Wilson. F. S. Geol. Surrey.)
device runs night and day without attention, except for oiling,
pumping 1,000 gallons per minute to a height of 16 feet, using
a 3/^- inch centrifugal pump, thus supplying more than 50 acre-
inches per day, or enough to irrigate 200 acres at the rate of
2.5 inches every 10 daj's. His plant is described as very effec-
tive, satisfactory and, for the amount of water supplied, cheap,
the total cost being $1,200.*
♦Bulletin Xo. IS, Wyoming Agr. Exp. Station.
SIO
Irrigation and Drainage
The very large sizes of hydraulic rams may also be used
on streams of relatively small fall for lifting water for the irri-
gation of small areas, especially if used in connection with
reservoirs. They are very simple, relatively cheap, durable, and
require but little attention. The ramming engines. Fig. 69, are
similar to the hydraulic rams, but are built larger and have
greater capacities. They are more complex in structure, and
more expensive. The engine represented in the figure is said to
be able to elevate water to a height of 25 feet for every foot of
fall, or to deliver one -third of the water used in its operation at
Pig. 70. Siphon elevator. (Wilson, U. S. Geol. Survey.)
two and one-half times the height of the fall, and one-sixth of the
water at five times the height of the fall. Those having a drive
pipe 8 inches in diameter and a delivery pipe of 4 inches are
capable, under a head of 10 feet, of elevating about 6 acre- inches
to a height of 25 feet in 24 hours, and this will irrigate 24 acres at
the rate of 2.5 inches every 10 days. Such an engine will cost
$500 (Wilson).
The siphon elevator, represented in Fig. 70, is an appliance
utilizing the principle of the hydraulic ram in connection with a
siphon. The amount of water lifted by this varies with the dimen-
sions of the appliance, the height to which the water is lifted, and
the difference between the lengths of the two legs of the siphon.
It can only be used where there is a dam, or similar condition,
Utilizing Stot'tn Waters 311
whieh permits a considerable difference between the long and
short legs of the siphon.
To start the action of the siphon, the long arm must be filled
with water ; then, as this descends again, more water rises
through the suction arm passing into the receiver (a) and through
the check- valve (e) into the regulator (b). In passing the cheek-
valve, the drag of the water closes it, and thus stops the current ;
but no sooner has this occurred than the momentum of the water
opens the puppet valve (d), and a portion escapes into the
storage tank or reservoir. While the tVater has been discharging
through the puppet valve and coming to rest, the fall of water
in the discharge arm has created a vacuum in the regulator,
whieh permits the atmospheric pressure on the corrugated heads
to force them inward and open the check-valve, thus starting the
flow again. These pulsations are very rapid, ranging from 150
to 400 per minute, so that a nearly continuous flow is maintained.
Wilson states that these water elevators have been built with
sufficient capacity to deliver 8 acre-feet in 24 hours, an apparatus
of this capacity costing $1,200.
UTILIZING STORM WATERS FOR IRRIGATION
There are many sections of country where the topography is
such as to permit storm waters to be caught by individual farmers
in reservoirs formed by cheap earth dams thrown across the
axis of a run, draw or ravine, and the floods produced by rains
held back and used in irrigating lands below in times of drought.
This is a very common practice in many parts of Europe, where
the collected waters are oftenest used on meadows. Suitable
arrangements are made for taking out the water, and a waste
weir is provided by which the water may escape before the height
of the dam has been reached.
Where water is supplied to large districts, the use of dams
with reservoirs is very common, especially on streams which are
subject to large fluctuations in volume during the irrigation
season.
312
Irrigation and Drainage
Fig. 71. Exposure of windmill whieli during one year pumped 79.1
aere-feet of water 12.85 feet liigli.
It will frequently happen, also, that streams or rills whose
volume of water is too small to be used advantageously may be
dammed arid the water accumulated in reservoirs, and used by
single individuals ; or two, three or more farmers may be located
so as to make it mutually desirable for them to unite their efforts
and take advantage of small streams in this way. So, too, may
the water of springs be led out to suitable places and accumulated
and warmed for use in irrigation.
WIND POWER FOR IRRIGATION
When relatively small areas of land are to be irrigated where
the lift is not greater than 10 to 25 feet, and where pumps may
be used of such forms and capacity as to economically utilize the
full power the mill is capable of developing, wind power may be
employed to good advantage in supplying water for irrigation.
Wind Power for Irrigation
31S
The writer* has conducted a series of observations with a
16-foot geared Aermotor windmill during one whole year, which
shows just how much water was lifted 12.85 feet high each hour
of every day under one set of conditions. The amount of the
water pumped each and every hour of the day, and the number of,
miles of wind which passed the mill and did the work, were auto-
matically recorded, giving for the first time a complete record for a
full year of the amount of work one windmill did in lifting water.
The mill stands on a steel tower 22 feet above the roof and
82 feet above the ground, as i>epresented in Fig. 71, and lifted
the water 12.85 feet from a reservoir having an area of 285
square feet, into a measuring tank holding 141.2 cubic feet,
which, when filled, emptied itself in 45 seconds back into the
reservoir. The number of times this measuring tank was filled
each hour of the day during each month of the year, and the
miles of wind which did the work, are given in the table on page
315, and the results are shown graphically in Fig. 72. In this
table the numbers at the head of the columns are the hours
♦Bulletin 68, Wis. Agr. Exp. Station.
7 » 1 to II m 1 2)«s-«79»/onM( jifj
lilt
800
^
N
r
\
^
1
\
/
\
/
\
,^1
'•
/
y
'
r-
— '
\
/
N
„^
^
V
^
■~^
-
^
1
N
^
A'
s
^
1
\
I.
_^H
\
/
I
V.
—J
_—
-—
-'
"~-
/
"->
Fig.
Upper eiu've shows miles of Tvind each hoiir of the year. Lower curve
shows the number of tanks of water pumped by the same wind.
314
Irrigation and Drainage
A B
Fig. 73. Aermotor 14-ineli reeiproeating pump used by windmill.
A, piimp ; B, piston head and suction valve.
of the day. The Hues of inimbers opposite the name of the
month express the total number of miles of wind for the hour
of the day at the head of the column, while the other lines ex-
press the number of times the tank was emptied during each Iiour
of the day. In the footings of the table, the upper line is the
total number of miles of wind during each hour of the day for the
full year; the second line is the'total number of tanks emptied.
Table shotoing the total number of tanks of water pumped each hour of the day
for each month, and the total vnnd movement in miles for the same time. <
Month.
Noon
1.
2.
3.
4.
6.
6.
7.
8.
9.
323,0
10.
11.
Mid-
night
4i!5.0
446,0
433
436,5
411,0
382,5
378.5
.365.5
332,0
322,0
293
319.0
113 4
112,8
Ui.S
101,6
94,5
80,1
61.8
67.0
60,3
46,0
62,7
50,1
50.9
r>21.5
512. S
476.0
476
403.0
436,5
392 5
394.0
363. C
424,0
431,5
464
412,0
157.0
153,?
138.
1.37,2
126,7
108,2
78.7
74.6
63.3
3.'), 8
103,5
108.5
90,3
May....
un.h
453,5
4.37,0
440 5
411 5
361,0
346.0
366.5
373.(1
373,0
375,0
3(>7,0
342.0
115 C
122,4
1 10 2
106,3
93 8
77,6
52.7
06.7
68.9
68,7
74,5
72 5
73.9
a2u.u
326 5
310,5
320.0
320,0
305,5
300.5
292.5
299.5
310,0
267,5
2(i7,0
292,5
ni
7«0
67,5
66,2
61,8
38,0
44.0
48,0
51.0
51.0
38,0
47.0
40.0
July....
328.0
351. -5
347,5
351,5
325.5
306,0
273.0
253,0
261.5
276.5
258,0
228.9
236,5
75.1
71.7
64.5
67,7
57,5
58,2
34.7
22.4
23 5
26.0
29,2
25,7
29,6
Aug
354,0
352
358,0
354
326,0
305,0
282.0
255.5
241.0
239.0
2i7,0
212.0
270.5
76.0
79,3
82,9
75 4
64,4
54
35.0
35.0
■MM
33.0
34,0
38,0
36.0
Sept....
339.0
354,0
362,0
351,0
331 ,0
276
246.0
256.0
271.0
264.0
272,0
252,0
251.0
89,6
101,6
96 7
93.1
82,1
49,4
30.6
30.3
37,3
37,0
40,3
33, V
HA
Oct
392.0
401,0
389,0
.376,0
359
313,0
341.0
355.0
342,0
350
329,0
314,0
325.0
107.2
lU.I
111 3
103,9
96 9
03,0
68.4
83.0
74 4
83,3
82,3
72,3
74,5
Nov
43(3.0
443,0
439.0
425,0
38S,0
345
359.0
373.0
363,0
.385
373,0
365.0
371,0
151.9
1.35
139.0
136,0
116,0
112.0
110
114.0
110,0
110,0
100,0
9t
92.0
Dec
395,0
389,0
359,0
331,0
326,0
329.0
334.0
339.0
3M.0
3.59,0
343.0
343,0
364.0
133,2
119,8
102 7
8U
79,8
8* 3
89.4
84.3
35,2
83,0
95,1
1(15,0
101.0
Jan
3S8.0
409
37,6,0
356
331,0
317
352,0
362.0
326,0
3.34,0
325.0
306.0
330.0
117,5
126,9
113,7
91 5
79,1
77,. 3
85.2
86.1
84,4
76.6
71,8
73,4
74.1
Feby....
4013.0
412.0
401.0
408,0
381
345,0
365.0
355,0
347,(1
363.0
368,0
365
392.0
119.2
131 1
48"i0.n
1.35
122,9
116,4
103,2
99.8
102.6
100.9
108.7
106,3
100,3
115.1
4741
4G93
4025,5
4318,0
4020,5
3969.5
3977.0
3335
4000.5
.3916,0
3.316.9
3905.5
1329 1
1346 5
1279,3
11SI.S!1069,0
907,3
790.3
814.0
793,7
809,1
837.7
8;u,5
,321. «
Correc'n
95,2
1424.3
9S,5
92 1
77 6 67.1
1259.4 1336.1
53
42.2
43.6
857.6
45.8
49.0
49,8
49. &
46,1
Totals
1445.0
1371.4
960.3
832.5
839.5
858.1
887.5
884.0
867.9
Month.
March ,
April ,
May
June
July .,.
August
Sept
Oct
Nov
Dec
Jan
Eeby
Correction*.
Totals
I.
3.
3.
4.
5.
G.
7.
8.
9.
10.
11.
Totals.
354.5
344.0
352.0
347,0
433,0
331,0
363,5
.383,5
410,0
427,0
388.
8765.0
64.9
54.9
55 7
56,9
53,3
64,3
75,1
74,0
85.1
95,3
84,4
1777,4
414.5
410.0
408.0
410.5
404,0
429,5
453,5
410.0
488.5
493,5
475
10(17.0
95,1
89.7
89 9
87.6
84 8
92,6
120.2
124.8
139.4
148,0
150,8
2648.5
3,34.5
3'24.5
329.5
347.5
353,5
356,0
389,5
397.0
409.5
435,5
410.0
9472.0
75,4
68.8
65,6
77.5
78,8
76,5
80,0
104.8
102 4
96.4
89,4
2035,6
269.0
278.5
275.5
261 5
269,0
281,0
3,53,5
322,5
310.0
291,5
297,0
7149,0
. 36,0
29.0
27,4
20.4
35
63,0
76.0
80.0
63,0
58,0
51.0
1242,7
220,0
215.5
211.0
208.0
218
227,0
247.5
258.0
286
311,0
319,5
6112,0
27,3
27.0
18,9
18.0
21 9
27,7
37.3
37,1
47.9
60,1
64,0
973,0
232.0
220.5
243,5
273.0
259,0
275,0
239.0
269.0
239,5
306,5
298.0
6702,0
26.0
30.0
37,2
42,2
31,0
36, C
44, C
48,0
57,0
62.0
60.4
1150,8
263,0
265.5
249,5
255.0
254, C
261. t
266 C
253. C
239,0
310,0
301,0
6591.0
44 1
45. C
43,4
61,4
45,2
,52„''
49. J
53 9
62,8
73,4
75,1
1378.5
316.0
309. C
307,0
284.0
265 (
283, C
273. C
312,0
318,0
;i5i,()
349.0
7934.0
72.4
69.2
66 1
55, C
45 7
57,.':
47.5
66 S
72,8
89,5
90.4
1869.4
372,0
as8.o
412 C
408,0
408, (
416, (
416. C
424.0
448,0
434,0
438.0
9303.0
102.0
107,0
102,0
96,0
95,0
108, C
126 C
129, C
142,9
148,9
115,6
2822.3
37S.0
377,0
372, C
352,0
3,30,1
353, C
3,38. C
340. C
349,0
370,0
380.0
8557.0
1(52. (J
104,5
103 t
91.6
85, t
99, £
83. C
94.1
99,0
115,2
110,5
2331.5
350,i,
354, C
334. C
325, U
339 C
348,C
335, C
365, C
334,0
389,0
374,0
8474.0
78 4
76,7
76,6
70,0
70, C
83,3
95.7
96.2
95,1
111,5
100.5
2112,7
405.0
396
419.0
397,0
384, C
383 C
384, C
373,C
390,0
332,0
343,0
9120,0
117.1
107 9
106,5
95 2
92,3
97,8
112,1
112,7
118,6
115,5
100,0
2646.2
3908.5
33,32,5
3913
3W>3,5
3916,5
3953,5
4058,5
4112,0
4371,5
4.501,0
4377,5
98905,0'
840.7
8U9,7
792, 3
772,4
738, S
860,2
956, S
1021,5
1086,0
1173.8
1122,1
22988.0
.50.8
47.1
44,1
41,6
40,2
52,6
63.5
66,6
72,3
82,8
73,9
891.5
8.56.8
836,4
814
779,1
912 8
1019,8
1088,1
1158,3
1256 6
1196.0
24433.0
*Approxiinate correction for water pumped during the time the tank was being
emptied.
316
Irrigation and Drainage
The total water pumped during the year by this windmill
enousrh to cover 79.1 acres 12 inches deep, thus showing an
average daily rate of 2.(5 acre-inches. The
largest amount of water pumped on any
single day was 39,540.2 cubic feet, or a rate
for 24 hours of 27.46 cubic. feet per min-
ute. There were short times occasionally,
however, when more water than this was
pumped, but the capacity of the siphon
was such as to cause it then to discharge
eontinuousl}-, and thus prevent a record be-
ing made.
Most of the water was lifted by two
pumps, working singly or in combination.
These were an Aermotor 14-inch reciprocat-
ing pump, worked on a 9-incli stroke, repre-
sented in Fig. 73, and a Seaman & Schuske
bucket pump, with 1 -gallon buckets, as
represented in Fig. 74. When the wind
was light the mill was given the bucket
pump, when stronger the I'eciprocating
pump, and when strongest both pumps at
the same time, and more work was ac-
complished in this way than would have
possible with any single pump.
74. Bucket irriga-
tion pump.
WATER PUMPED DURING 10-DAY PERIODS
Since the availability of wind po\Yer for irrigation is limited
not so much by the total work of the year as by the water
which may be pumped in times of special need, a clearer idea
of the possibilities of wind power for irrigation can be gained
by tabulating the work done during the year by 10-day periods.
This has been done in the table which follows, but firs-t reducing
the results to a lift of 10 feet instead of 12.85 feet, the height
the water was actually raised :
^yi)l(l Power for Irrigation
317
Table showing computed amount of teater lifted 10 feet high during consecutive
10-day periods for one full year, expressed in acre-inches
Feb. 28-Mcli. 10.
iMch. ItKJO
Mcli. "JO-oO
Meh. yiHApr. 9. .
Ai'f. 9-19
Apr. ]y-'J9
Apr. 29-May9...
May 9-19
May 19-29
May 29-Juiie8..
June S-18
June lS-28
June 28-JuIy 8. .
Water !i
pumped I
I Water 1
pumped
\Acre-in.
33.540
36.620
52.77
47.01
54.11
63.05
59.97
28.69
51.38
40.54
27 59
13.82
26.68
July
July
July
Aug.
Aug.
Aug.
Sept.
Sept.
Sept
Oct.
Get.
Oct.
Nov,
8-18 21.53
18-28 29.73
i8-Aug. 7 ..
7-17
17-27
27-Sept.6..
.6-16
. 16-26
. 26-Oet. 6..
6-16
16-26
26-N'ov. 5...
5-15
9.87
36.26
20.20
21.27
18.00
40.42
23.79
55.07
18 45
36 71
49.49
Nov. 15-25
Nov. 2.'>-I)ee. 5 .
Dee- 5-15
Dec. 15-25
Dee. 25-Jan. 4.
Jau 4-14
Jan. 14-24.
Jan. 24-Keb. 3..
Feb. 3-13
Feb. 13-23
Feb. 23-28
Water
pumped
52.77
47.46
39.52
31.18
51.22
33.92
29.16
59.36
33.45
75.73
16.20
E-eferring to the table, it will be seen that the smallest
amount of water pumped in any 10 days was 9.87 acre-inches,
this occurring between July 28 and August 7. at a time when
most water is needed. In this jieriod there were 7 full days
when no water was pumped, all the water being raised during
3 days of the period.
The mean amount of water pumped during the 100 days
from May 29 to September 6 was 24.5 acre-inches per 10 days,
and as this is the season in the United States when most water
is needed lor irrigation, the figure may be taken as rejireseuting
the capacity of such a pumping system. That is to say, such a
plant is able to supply 10 inches of water to 24.5 acres during
100 days when the lift is 10 feet, and to 12.25 acres where the
lift is 20 feet. If the crop irrigated demands 20 inches of water
in 100 days, then the area which could be supplied under a
10-foot lift would be only 12.25 acres, and under a 20-foot lift
only 6.12 acres. It must be understood, however, that these
results are possible only under conditions of no loss between the
pump and the land to which the water is applied.
From theoretical considerations and the above data, it
appears probable that for different sizes of wheels and for dif-
ferent lifts, but under otherwise similar conditions, areas may
be irrigated as given in the table below.
318 Irrigation and Drainage
y umber of acres a first-class windmill may irrigate to a depth of 10 inches
and 20 inches in 100 days
Lift 10 feet Lift 15 feet Lift 20 feet
Diam. of 10 ins. per 20 ins. per 10 ins. per 20 ins. per 10 ins. per 20 ins. per
wheel 100 days 100 days 100 days 100 days 100 days 100 days
8.5 ft. 2.40 1.20 1.60 .80 . 1.20 .60
10 ft. 7.58, 3.79 5.06 2.53 3.79 1.90
12 ft. 13.61 6.81 9.08 4.54 6.81 3.40
14 ft. * 17.44 8.77 11.70 5.85 8.77 4.39
16 ft. 24.50 12.25 16.34 8.17 12.25 6.13
In computing this table for other sizes of wheels, we have
used the ratios calculated by Wolflf ; * but as our observed work
is about 12 per cent less for the 16 -foot wheel than he com-
putes for this size, the values in the table are correspondingly
lower than his table would give. It is the writer's conviction,
however, that the results he has observed for the 16-foot
wheel are quite as high as will be likely to be realized by
average practice with the pumping devices of to-day.
NECESSARY COXDITIONS FOR THE HIGHEST SERVICE
WITH A WINDMILL
In order that the largest service may be secured from a
windmill, there are certain essential conditions which must be
observed First among these is a good wind exposure. It is
useless to purchase a windmill and then set it up in such a
manner that the wind cannot have free access to it. Strong
towers, having a height of 70 to 90 feet, should usually be
used, and these placed where hills, groves or other obstructions
cannot break the iforce of the wind.
Second in importance to a good exposure of the mill is a
pumping outfit thoroughly adapted to the power of the mill. It
should not be so heavy as to force the mill to stand idle in winds
of 9 miles per hour, and yet it should be capable of utilizing
the full power developed in a 25- to 30 -mile wind.
*A. R. Wolff, the Windmill as a Prime Mover.
Wind Power for Irrigation 319
If reciprocating pumps are used, the strokes should be made
as long as possible and the number not higher than 20 to 25
per minute, to avoid loss of energy in pounding. Suction and
discharge pipes should, as a rule, be as large as the cylinder,
and where water is to be raised above the surface, this should
be done by carrying the discharge pipe up into the tower to
the necessary height to avoid the use of stuffing boxes. The
large wooden plunger rods, which displace one-half the volume
of the water raised with each stroke, are in the direction of
economy in making the pump in a measure double-acting. If
a screen must be used over the end of the suction pipe, it should
be given large capacity, and be carefully watched, to see that
it does not become clogged. All valves should have large
ports, easy action, and be tight fitting, so that every stroke,
whether slow or quick, shall discharge the full capacity of the
cylinder.
There should be two pumps of different capacities, so arranged
that either may be used alone, or the two used at once, thus
providing three loads-, to be applied when the wind is light,
medium or strong. This can readily be arranged by attaching
the lighter pump directly to the mill and the larger one to a
walking-beam ; or both may be attached to a walking-beam,
one end of which is carried by the driving rod of the mill.
The geared windmills may readily be made to work a pump
of the bucket type. Fig. 74, and if the buckets can be provided
with valves which do not leak, a pump of large size may
be used, speeded back so as to be driven by the mill in the lighter
winds, and with increasing speed in the higher winds, without
reaching the limit at which the buckets fail to empty.
But as the power of the mill increases more rapidly than
the velocity of the wind, what is needed is a device which
is capable of increasing the load more rapidly also. Attaching
an additional pump secures this end, but the objection to the
plan is that it is not automatic, and much service must be lost
by the mill being either too heavily or too lightly loaded until
an attendant can make the change. Still, this plan is worth
following until something better can be had.
320 Irrigation and Drainage
THE USE OF RESERVOIRS
To employ •wind power for irrigation to the best advantage,
a reservoir is required in most eases. Thei-e are localities on
the seashore where nearly every day a sufficient breeze springs
up to drive the windmill, and in such cases, if the supply of
water is large, the lift small, and the demand for water moder-
erate, the ground for many crops may be laid out in such a
manner that a system of rotation may be followed, and the
reservoir dispensed with ; but in such eases the time and
attention required for the distribution of the water will usually
be greater than where a reservoir is used.
The reservoir should be placed where it is high enough to
serve all the ground to which it is desired to supply water, but
it is very important to keep it just as low as possible, because
since the economic lift of the mill is only 10 to 25 feet, every
foot saved on the height of the lift into the reservoir is a large
percentage gained in efficiency. The elevated wooden tanks,
placed on towers far above the ground to be irrigated, are very
expensive in themselves, and greatly reduce the area which a
windmill can irrigate.
In constructing a reservoir where soil and subsoil are
reasonably fine and close, the first step is to remove from the
area all rubbish and coarse litter that may interfere with the
close packing of the soil. The land upon which the walls of the
reservoir are to be built is then plowed, leaving a dead furrow
in the center, which may be filled with water until the whole
area is thoroughly saturated. When the water has drained
away sufficiently to permit of teams driving over the ground,
the soil should be thoroughly trampled and puddled, after which
dirt from the bottom of the reservoir may be scraped on and
trampled with the teams continuously and thoroughly. It is
recommended as an excellent plan to maintain the sides of the
walls higher than the center, but all portions nearly enough
horizontal, so that water may be pumped into the furrow at
night, to help in settling the materials more closely and render
the puddling more complete.
The Use of Beservoirs 321
After the walls have been raised to the proper height, the
bottom of the reservoir is plowed, harrowed fine, and the whole
flooded with water, if practicable, to better fit the soil for
puddling. In ease the soil is at first too open for flooding all
at once, the water may be led in furrows close together, filling
as many at a time as the capacity of the pump will permit,
turning the water into others when a sutScient saturation has
been reached. When the bottom of the reservoir has been
thoroughly puddled over the whole area and continuous with the
puddled bottom and sides of the walls, there will usually be but
little loss from seepage.
The sluice for taking out water for irrigation should be laid
in the wall at the level of the ditch outside which carries the
water to the fields or garden, but at some distance above the
bottom inside, so that the water may not be entirely withdrawn
and permit the sun to dry the soil, thus destroying the effect of
puddling. In cold climates, it is also important to retain enough
water in the reservoir to prevent the bottom from freezing, as
this may destroy the effect of puddling.
The sluice should project entirely through the walls on both
sides, and be provided with a suitable gate or valve for closing
and opening it, either fully or only in part, according to the
amount of water needed, and the dimensions should be such as to
permit more water to be taken out than is likely to be needed.
The most thoroughly satisfactory and permanent outlet for
a reservoir can be provided by using wrought iron pipe of suit-
able size, provided with an elbow at the inside, which opens
upward. This may be closed by means of a plug worked by a
T lever or handle, keeping the threads well protected with
cylinder or wagon grease, to prevent rusting in.
Oftener the sluice is made of 2-ineh plank, tightly put
together and provided with a gate, as represented in Fig. 75*.
In other cases, the mouth of the sluice is cut off obliquely, and
a gate is hinged to the upper side and provided with a handle
reaching above water, to which a cord is attached for opening
♦From Bulletiu No. 55, Kansas Agr. Exp. Station.
U
322
Irrigation and Drainage
the gate by simply pulling upon it. This is very simple and
easily operated. In placing the sluice in the wall of the reser-
voir, great care is needed to get the dirt thoroughly tamped and
puddled about it, so that water shall not follow its sides and
develop a leak.
To prevent injury from waves, the walls of the reservoir
should be sloping and not steeper inside than a rise of 1 in 2.
Fig. 75. Sluice and gate for reservoir. (Kansas Aarr. Exp. Station.)
At the outlet ditch there should be provided an overfow weir
suflBciently below the top of the wall to prevent wave action
from starting a cut in the top by breaking over. A reservoir,
completed and filled with water, is represented in Fig. 76,
but where these are made circular in form there must be less
seepage through the banks in proportion to the amount of water
stored, because less wall is required to enclose a given area
when this is circular.
The Use of Reservoirs
323
The amount of seepage from reservoirs must vary with the
character of the soil, but Carpenter cites a case where the loss
from this cause did not exceed 2 feet for a whole year, and
this is satisfactorily small.
Where the soil is very open and sandy, it may be necessary
to haul on clay or fine soil to use in puddling, or the reservoir
may require covering with coal tar, asphalt or cement. These
Fig. 76. Rectangular reservoir for windmill irrigation.
materials, however, are expensive, and usually not within the
reach of small irrigators.
The loss of water from a reservoir by evaporation in dry,
windy climates is much larger than the necessary seepage, and
this can only be lessened hy planting windbreaks about the
reservoir.
A circular reservoir 4 feet deej) and 40 feet in diameter will
supply .35 acres with 4 inches, and .09 acres with 2 inches of
water. One, 100 feet in diameter and 4 feet deep will irrigate
4.32 acres with 2 inches of water and 2.16 acres with 4 inches,
while a reservoir 209 feet on a side and 4 feet deep will supply
water enough to irrigate 12 acres with 4 inches of water, 16
acres with 3 inches, and 24 acres with 2 inches.
324
Irrigation and Drainage
PUMPING WATER ^^'ITH ENGINES
The amount of water -whicli was pumped l)y a 16-foot geared
windmill with a lift of 12.85 feet has heen given as 79.1 acre-
feet as the work of a year.
A 2/^ horse-pov.-er Webster gas engine was used on the same
pumps with which the windmill did most of its work, and with
the same lift, to see what amount of water could be supplied hy
such a power. During a 6-hours' run the engine lifted 13,202.2
cubic feet 12.85 feet high, with a consumption of 458 cubic feet
of gas costing $1.25 per thousand, or at a rate of 95.4 cents per
day of 10 hours.
At this rate of pumping and cost
for fuel, the engine could supply in
100 days 50. G7 acres with 12 inches
of water at a cost for fuel of $95.40
or $1.88 per acre for the season, and
$3.76 where 24 acre-inches of water
is applied.
On our own place the same make
and size of engine as that used aVjove,
and represented in Fig. 77, but using
gasoline at 9 cents per gallon for
fuel, and lifting the water against a
head of 50 feet with a double-acting
pump, discharging 75 gallons per
minute, the cost for a 96 -hours' run
\v4is $4.95.
The water pumped in this time
was 432,000 gallons at the rate of
$1 for 3.214 acre-inches. In 100
days of 10 hours this plant would
lift, under its conditions, 601,605 cubic feet of water, or 13.81
acre-feet, at a cost for fuel of $51.56, thus making the experse
$3.73 for 12 inches in depth of water per acre, and $7-46 for 24
inches.
Fig. 77. Webster 2V2 liorse-power
vertical gasoline engine.
Fig. 78. Persian wlieel for lifting water. (Wilson, U. IS. Geol. Survey.)
Fig. 79. Bucket pump for use with horse power. (Wilson, V. 8. Geol. Survey.)
326 Irrigation and Drainage
Such a putuping plant as this would easily irrigate 10 acres
12 inches deep and 5 acres 24 inches deep without the aid
of a reservoir, and with the aid of a reservoir the area could
be made 15 acres or 7.5 acres, according to amount of water
used.
For the field irrigation on the Wisconsin Agricultural Experi-
ment Station farm, we have used an 8 -horse -power portable
steam engine driving a No. 4 centrifugal pump. Soft coal at
$4 per ton has been used for fuel, and with a lift of 26 feet,
drawing the water through 110 feet of 6-inch suction pipe and
discharging it through varying lengths of the same pipe up to
1,200 feet, the coal consumed has been at the rate of one
ton for an average of 80,210 cubic feet, or 22.1 aci'e-inches.
At the above rate the fuel cost of an acre -inch of water is
18.1 cents, making 12 inches of water amount to $2.17 per acre,
and 24 inches $4.34 as the cost for fuel.
Willcocks states that taking the mean of some 60 observa-
tions carefully made in the delta and Upper Egypt, the actual
discharge obtained for a 4-meter lift is 480 cubic meters per
horse-power per 12 hours, taking the 8-horse-power engine as
the standard, and he italicizes tliis statement : "^ discharge of
480 cubic meters j)er nominal liorse-poxrer per 12 hours is the mean
in Eoiipt."
He also estimates the cost of working a 10-horse-power
engine in the interior of Egypt as follows :
£ $
Driver and stoker, per day 15 .73
Oil, etc., per day 05 .24
Coal, away from canals per day 1.00 4.84
sI^t; of 10 per cent per annum on cost of engine,
for depreciation, repairs, etc 10 .48
Total £1.30 $6.29
The amount of water pumped by the 10-horse-power engine
to a height of 13.12 feet is 3.891 acre-feet, which from the
above table makes the cost per acre -foot $1.62 where the ground
is covered to a depth of 12 inches, and $3.24 per acre where
the depth is made 24 inches.
Methods of Pumping
327
Pig. 80. Shadoof of Egypt, or Paeeottah of India. (Wilson,
U. S. Geol. Survey.)
Taking an average 8-hour day for pumping, the above
pumping plant should irrigate during a 100 -day season 259.4
acres to a depth of 12 inches and 129.7 acres to a depth of
24 inches, at a total cost for pumping of $420.23.
328
Irrigation and Drainage
THE USE OF ANIMAL POWER FOR LIFTING WATER
FOR IRRIGATION
Many and very old are some of the devices invented to
utilize both human strength and that of cattle and horses.
Fig. 78 represents the Persian wheel, very extensively used in
Asia Minor and in Egypt for lifting water, two cattle raising
as much as 2,000 cubic feet per day on low lifts. A more
;^I^^^S^?5^r^' ' r"^:-^^
Fig. 81. Doon of India. (Wilson, U. S. Geol. Survey.)
modern device is represented in Fig. 79, wliere one horse may
elevate through a height of 20 feet 500 cubic feet of water per
hour and 5,000 per day of 10 hours, or a rate which, if followed
for 100 days, would give more than 11 acres 12 inches of water
in depth.
Much land is ii'rigated in India, Asia Minor and Egypt,
where the water is lifted by man-power, and Figs. 80 and 81
show two of the forms of lifting devices upon which men are
worked. Two men, working alternately, are said to irrigate an
acre in 3 days with the shadoof, lifting the water about 4 to 6
feet.
CHAPTER X
METHODS OF APPLYING WATER IN IRRIGATION
When v/ater has been provided for irrigation and
bronght to the field where it is to be applied, the
steps which still remain to be taken are far the most
important of any in the whole enterprise, not except-
ing those of engineering, however great, which may
have been necessary in providing a water snpply
which shall be constant, ample and moderate in cost ;
for failnre in the application of water to the crop
means utter ruin for all that has gone before.
To handle water on a given field so that it shall
be applied at the right time, in the right amount,
without unnecessarily washing or puddling the soil or
injuring the crop, requires an intimate acquaintance
with the conditions, good judgment, close observation,
skillful manipulation, and patience, after the field has
been put into excellent shape ; and riglit here is
where a thorough understanding of the principles
governing the wetting, puddling and washing of soils,
and possible injury to crops as a result of irrigation,
becomes a matter of the greatest moment. There is
great need of more exact scientific knowledge than w«
now have to guide the irrigator in his handling of
water.
(329)
330 Irrigation and Drainage
PRINCIPLES GOVERNING THE WETTING OF SOILS
Wheu water is applied to a soil which becomes
more open in texture and coarser grained as the depth
below the surface increases, it will travel downward
in nearlj- straight lines, and will spread laterally but
very little except by the relatively slow process of
capillarity. This fact is forcibly illustrated in Fig.
82, where the experiment consisted in maintaining the
level of the water in a hole at the place designated by
the arrow until 200 cubic feet had percolated into the
soil. The heavily shaded area in the figure shows
the mass of soil completely filled with water on the
two dates, October 15 and 17, while the water was
running. It will be seen that although the hole was
kept full and the water-level within 8 inches of the
surface, the water did not spread sideways more than
2.5 feet until below a depth of 11 feet.
If we imagine this to represent a cross -section of
the soil under a water-furrow extending across a
field, it will be readily seen how much water would
be lost by rapid percolation directlj' downward, and
how little, even after a long time, would have spread
laterally to wet the field. To irrigate such soils satis-
factorily and economically, the water must be spread
over the whole surface, or be led in furrows which
are near together across the field, so that the soil
between the furrows may quickly become wet.
While the water is in the furrows, it will travel
sideways by capillarity fastest in those soils which are
coarsest, for the same reason that it flows downward
Principles of Wetting ISoil
331
fastest ; namely, because the pores are largest and
offer less resistance to the flow. The truth of this
statement will be readily apprehended by studying
Fig. 83, which shows how greatly the diameter of the
Fig. 82. Slow rate of lateral spread of water in soil.
waterways in a soil is modified bj' the size and ar-
rangement of the soil grains. This being true, it is
plain that water should be moved most rapidly over
the coarsest soils, in order that unnecessary waste by
deep percolation may not take place.
332
Irrigation and Drainage
If a soil decreases in fineness of texture as the
depth increases, then there ma}' be a considerable
lateral spreading of the water due to gravity, and
Fig. So. Size and arrangement of soil grains as influencing iK)re space
and capillary ■waterways.
this, aided by capillarity, will permit the furrows to
be placed farther apart and the water to be run more
slowly over the ground.
Where a fine, loamy soil is underlaid at 3 to 5 feet
with a subsoil of much finer texture, through which
the water percolates slowly, then water may be led
quite rapidly through furrows some distance apart and
considerable quantities applied at once, depending
upon it to spread laterally by gi-avity, and to rise by
capillarity under the spaces between the furrows, in
this way wetting tho larger part of the soil of the
Principles of Weliiny Soil 333
field by a sort of sub -irrigation, which should be
utilized to the fullest extent possible, for then tlie
intervals between irrigations may be longest and the
duty of water will be highest.
If the soil is allowed to become very dry before
watering, especially if the texture is close and the
grains fine, water will percolate downward less
rapidly, and it will move sideways and rise under the
influence of capillarity more slowly, because the air of
the soil must be displaced ahead of the water.
A fine soil, flooded under these conditions, will
take water \qvj slowly, because the surface pores be-
come filled with water, which is retained with so
much force that air bubbles cannot readily rise through
it, and the conditions are similar to a jug filled with
air bottom upwards under water, — the one cannot
escape nor the other enter. Such soils, therefore,
which must be flooded should not be allowed to reach
this di'y condition. The case is not so bad when
furrow -irrigation is practiced, because the water pres-
sure in the furrow may displace the air laterally
where it can escape upward between the furrows
unhindered by the water.
On the other hand, there are conditions when it is
desirable to take advantage of this hindrance of air
to percolation. Where a clover, alfalfa, grass or grain
field must be watered by flooding, and where the head
of water is small, the fall slight, and the distances
the water must be led long, the spreading will be
much more rapid and better when the surface soil has
become dry. Indeed we have repeatedly tried to
334 Irrigation and Drainage
water a certain piece of land when the surface soil
was yet quite moist, and found it impossible to do so
with the available head, because the water would sink
into the ground faster than it could be supplied ; but
by letting the soil become dryer the same head spread
the water easily over the whole area, wetting it
evenly, though there was greater hindrance from the
clover having become thicker and larger.
In furrow irrigation, the same principle may be
taken advantage of in cases where the rows are long
and the head of water too small, though not to the
same extent ; but the difference is sufificiently pro-
nounced to be sometimes quite helpful in open soils.
PRINCIPLES GOVERNING THE PUDDLING OF SOILS
A puddled soil is one in which the compound soil
kernels or crumbs have been broken down more or
less completely into separate grains and run together
into a closely compacted mass. Such a soil may hold
its pores between the grains so completely filled with
water until lost by evaporation that little free air
is present except that absorbed in the water itself. In
such a soil roots quickly suffer for lack of air, the
process of nitrification cannot go on, and, what is
even worse, the nitrates already present in the soil
when the puddling occurred may be rapidly lost by
the process of denitrification.
The water-logging of a soil has the same dis-
astrous effects regarding the roots of plants and on
the processes of nitrification and denitrification. Both
The Puddling of Soils 335
conditions should, therefore, be studiously avoided by
every irrigator.
If soils to be irrigated coutaiu black alkali, and
this has been permitted to accumulate at the surface
during the interval between waterings, it is evident
that the flooding of such soils will redissolve the
alkali, and as this, in solution, tends of itself to pro-
duce puddling, it is evident that the irrigation of
such lands should always be done with the greatest
care, in order not to complicate the difficulties of the
crop by adding that of a puddled soil to the dele-
terious action of the carbonate of soda.
It is extremely difficult to completely submerge
a recently stirred soil of any kind without breaking
down the crumb structure so essential to perfect tilth,
and all are familiar with the fac^t that there is no
way to so effectually compact loose soil in a trench
as to completely fill it with water. It is, therefore,
plain that soils should be watered before plowing
and fitting, when the running together cannot take
place, rather than after the ground is seeded. Indeed,
water enough should alwaj^s be present in a soil at
seeding time, not only to germinate the crop, but to
carry it well on in growth, so that if baking of the
soil must take place, less harm will be done. There
are few soils which it would be safe to flood just
after a crop like oats, wheat or barley is up, for fear
of packing the soil and seriously injuring the crop.
When the plants have attained some size, when
the soil has gained in firmness by the natural pro-
cesses of settling, and when the roots have spread
336 Irrigation and Drainage
and occupied the soil, the shading, the fii-iiiing and
the root binding all conspire to prevent puddling
and baking, so that flooding ma^- then be practiced
with less danger of harm ; and so grass lands, alfalfa
and clover may always be flooded with little danger
of injuring the texture of fhe soil, because the exten-
sive root systems prevent it.
When water is applied in furrows without wash-
ing, so that it rises and spreads through the soil
between the furrows by capillaritj-, it then has the
opposite effect from puddling, and tends rather to
improve the texture by drawing the loosened soil
grains together into clusters by an action of surface
tension like that which rolls drops of water into spheres
on a dusty floor. As the soil crumbs become satu-
rated with capillary water the loose dust particles which
have been formed in tilling are drawn to them and
bound closely by the pull of the surface film ; but
so soon as the whole soil becomes immersed in water,
as in the case of flooding, and as happens in the bottoms
of the furrows, there is then no surface tension, and
the soil grains fall apart under the water of their own
weight, and compacting and puddling are the results.
It follows, therefore, that all crops where the
ground is not covered by them, and where cultivation
is resorted to to prevent loss of water by evaporation,
should so far as pi'acticable be irrigated by the fur-
row method ; and since the bottoms of the furrows
must be subjected to the conditions which puddle,
it follows that the furrows should alwaj's be as far
apart as other conditions will permit.
The Washing of Soils 337
PRINCIPLES GOVERNING THE WASHING OP SOILS
One of the commonest mistakes of beginners in
irrigation is the use of too large volumes of water
in a place and hurrying it over the ground too
rapidly. It must be kept ever in mind, in all sorts
of irrigation, that the eroding and transporting power
of water increases with the velocity with which it
moves, but in a higher ratio ; to double the rate at
which "svater moves in a furrow or over the surface,
increases its power to wash and carry the soil for-
ward nearly fourfold.
In good irrigation, the water, is forced to move
so gently that it runs nearly or quite clear and with-
out washing the sides or bottom of the furrows, and
if one does not succeed in securing flows without
washing, the only conclusion which should be drawn
is that the right way has not yet been learned, not
that it cannot be done.
Naturally, the steeper the slope of the furrows
the faster the water tends to run. So, too, when the
slope remains the same, the larger the volume of water
in the furrow the faster the water will flow, and these
two principles give the irrigator nearly complete con-
trol of the situation.
If the ground is flat and the water moves too
slowly, increase the amount in the furrow, and if
there is not water enough to do this, decrease the
number of furrows handled at one time. If the water
runs too fast and washes, divide up the stream, lead-
ing it into more furrows until the movement comes
338 Irrigation and Drainage
to be the rate which does not wash or erode. We
have seen orchards in the foothills of California irri-
gated by carrying the water in furrows down the hill
where the slopes were too great to readily plow with
a team and yet it was done with such skill that no
appreciable wash was produced, neither did anj^ water
run to waste. Everything was adjusted with such
nicety that by the time the streams had reached the
ends of the furrows the whole of the water had been
absorbed by the soil. The 30 acres referred to were
owned and managed by a Swede, and when he was
asked if he did not find it difficult to handle the water
so as not to wash his soil and waste the water on
these steep hills, with no grading or terracing, the
reply was : " Easy now ; , but was very hard when I
didn't know."
The most essential point in the distribution of
water is to have the furrows on a nearly uniform
slope, so that the velocity of flow will be closely
uniform through their entire length. If the same
grade cannot be secured throughout, it is better to
change from a steeper slope to one more flat than
the reverse, because then the reduction in velocity
will be partly made up by a greater depth of water
in the furrow on the flatter reaches,
FIELD IRRIGATION BY FLOODING
When large areas of land are to be irrigated in
single blocks, there is no method of applying water
which is so economical of labor and of time as the
340 Irrigation and Drainage
systems of flooding, whenever it is possible to estab-
lish and maintain the best conditions for them, and
there is no other system which permits of so nni-
form a wetting of the surface.
There are two fnudameutally different systems of
flooding. One covers the surface of a field with a
thin sheet of running water, maintained until the
desired saturation has been reached ; the other covers
the surface with a sheet of standing water, which is
allowed to remain until the soil has absorbed enough,
when the balance is drawn off ; or, simply as much
water as is desired is placed upon the land, and this
remains on the surface until it is absorbed.
The two systems are used most for crops like
the small grains, grasses and clovers, which closely
cover the ground, and where intertillage is not practiced.
They are also used extensively where fields for any crop
must be moistened preparatory to plowing and seeding.
Flooding by running water is practiced with great
nicety and thoroughness on large fields of 40, 80 and
even 160 acres in the old Union Colony at Greeley,
Colorado. Here, usually, the natural slope of the
country is good, and a distributiug ditch is carried
along the highest edge of a field to be irrigated.
When the time for watering has arrived, the field is
divided into lands of 60 to 120 feet by parallel fur-
rows, made by using a wide V-shaped plow, throwing
the earth both ways, thus forming distributing fur-
rows, represented in Fig. 84, about 30 inches wide at
the top. These furrows are made rapidly with a 3-
or 4 -horse team, and when a crop of grain is ready
Field Irrigation hij Flooding
341
to cut, a coininon plow is driven up one side and
down the other of the furrow, thus filling it and
leaving the field in shape to be driven over with the
harvesting machine. The ridge of earth on each side
of the distributing furrow serves the purpose of
Fig. 85. Canvas dam taken up.
borders, to the lands, Avhich prevent the return of
the water to the furrows after it has been thrown
out by the dam, shown at the point where the man
stands in the cut.
This dam is simply a piece of canvas tacked by
one edge to a strip of wood 2x4 inches in thick-
ness and 6 or 8 feet long, as seen in Fig. 85.
342 Irrigation and Drainage
When in use, it is laid in the furrow with the canvas
up stream and the free edge loaded with earth to
hold it down, when it effectually holds back the water
and throws it out upon the strip to be watered.
Water is turned into one, two, three or more of
these distributing furrows from the head ditch,
according to the amount available, and when the
lands have become sufficiently wet as far below the
canvas dams as the water will readily flow through
the grain or grass, these are picked up and moved
farther down and the stream again turned out.
Water is thus led over successive lands until the
whole field has been irrigated easily, rapidly, cheaply
and, at the same time, well.
Where crops are grown in short rotation on a
large scale, as they are at Greeley, wheat, alfalfa or
clover and potatoes following one another in regular
order, it is doubtful if a better or more satisfactory
system of irrigation can be devised than the one
described.
If the slopes of the field are steep, and especially
if thej- incline in various directions, then the small
grains and grasses may sometimes be irrigated better
by the method represented in Fig. 86, where water -
furrows are thrown across the surface of the slope
nearly along contour lines, giving them only so much
fall as is needed to lead the water forward.
These furrows for grain fields, where they are tem-
porary, would be best formed with the ordinary plow,
at the time of seeding, and the upturned earth
smoothed down, so that it may become set before the
Field Irrigation by Flooding
343
water must be led across it. Where help is scarce
and the price of the crop sniall, it is often the prac-
tice to enter the field with the plow just before the
water is to be applied, and form the furrows then.
In watering by this method, the aim is to throw
Section
EF
J
Fig.:
Flooding field on steep slopes. (iTi-unsky.)
the water over the lower edge of the furrow in a
continuous sheet or else at short intervals, to flow
down the slope until the portion of the field within
reach has received what is needed. To do this,
canvas dams or temporary earth dams are used, as
344 Irrigation and Drainage
described above ; then, when the water is to be carried
forward, the dams are also shifted
As represented in the figure, water may be carried
directly down the slope across a series of secondary
furrows, as at C, D, D, D, and the main supply fur-
rows may be set one below another at such intervals
as the extent of the fields and the slope of the
surface \\va\ demand. In the figure, a second water
furrow is marked "supph' and drain ditch," but if
the best work is done in handling the water, there
should be no surplus to drain away.
When slopes like those under consideration are
in permanent meadows or pastures, or if they are in
meadows for three or more years, it will be best
usually to give more time to shaping the furrows,
so that washing will not occur when less attention
is given, and so that the mower and horse rake may
readily work over and across them.
In European countries, where so much labor is
done by hand, little attention has been paid to
developing systems of applying water to fields which
will readily permit of the use of machinery, as must
be the case in this country, at least for a long time
to come.
Where grain fields are not very long, and where
the slope is gentle and uniform, the water may be
distributed from a single head ditch by simply mark-
ing the field, after it has been sowed, with a tool
like the corn -marker, but having runners close enough
to give shallow furrows every 15 or 20 inches.
These shallow furrows lead the water forward in par-
Field Irrigation by Flooding 345
allel lines from which the lateral spread may be, to
a large extent, by capillarj^ creeping, and they guide
the flow past minor inequalities, preventing the water
from becoming concentrated so as to do injury
through increase in volume and velocity and from
running around areas, leaving them dry. This inark-
ing is so rapidly and cheaply done, and obstructs
the surface so little, that it is to be highly recom-
mended where applicable.
A corrugated roller might be used instead of the
sliding marker to form the water lines, but this
would have no tendencj- to throw the kernels of grain
to one side, and the channels would be more obstructed
by the plants. Neither could so great a depth be
secured, especially on heavy soils not deeply and
recently worked.
In the second flooding system, where the water is
made to stand over the whole surface to any desired
depth, the fields must be laid out in areas bounded by
ridges or low levees, which check the flow of water
and hold it as in a wide and extremely shallow
reservoir.
The size of the checks in which a field is laid out
will be determined by its general slope, by the head
of water available, and by the height of the levees or
check ridges. It is desirable, for meadow and grain
irrigation, to make the checks as large as practicable
and at the same time to keep the ridges so low
as not to interfere with the movement of farm
machinery over the field.
If the slope of the field is 6 inches in 200 feet,
346 Irrigation and Drainage
and it is desired to place the upper edge of each
check under 2 inches of water, it would be neces-
sary to construct the levees, for checks 200 feet
square, about 10 or 12 inches high, because the water
would be 8 inches deep on the lower edge when the
surface was covered 2 inches at the higher side, and
a margin of 2 to 4 inches is needed for safety
against the water breaking across over slight depres-
sions or against wave action.
If the fields are to be used continuously for mead-
ows, pastures, alfalfa, or either of these, in rotation
with small grains or similar crops which may be best
irrigated by flooding, it will usually be desirable to
make the check ridges broad and flat, so that mowers
and harvesters and even plows may readily move over
them. They thus become permanent features of the
field. If a 20-, 40- or 80-acre field is to be laid off
in regular checks, this would probably be most rapidly
and cheaply done by a system of plowing in repeated
back -furrows until the desired height of ridges is
reached. The sizes of the checks would first be deter-
mined, and then all the ridges extending in one
direction formed, first at the distance apart found
desirable, after which the field would be crossed in
the other direction, forming in the same manner the
other sides of the checks.
In cases where a single plowing does not give
sufficient height to the ridges, and in countries
where the rainfall is sufficient to permit moderate
crops to be grown without irrigation, the labor of
fitting the ground in this way may be made a part
Field Irrigation bij Flooding 347
of the regular plowing for the crops, and permitted
to extend through a number of years, thus making
the expense of fitting the ground for irrigation
mainly that of fitting the land for crops. By this
plan the field would be plowed in lands in one direc-
tion, with the back furrows always in the same place,
until the desired height is attained ; then these back
furrows would be crossed to form the other sides of
the checks, plowing in the same manner.
In case the checks are large, the land between
the ridges maj' be subdivided and plowed in the
ordinary way, letting the back furrows and dead
furrows alternate in position with the seasons, in the
usual manner. There will be some finishing work
required, especially where the check ridges cross one
another.
It is not, of course, necessary that the flooding
checks shall be square. If the field has a consider-
able fall in one direction and little or none in the
other, the checks may be made much longer in the
nearly level direction, and thus reduce the labor and
inequalities in the field.
In cases where the slopes are more or less undu-
lating, the check ridges which are horizontal will
necessarily follow the course of contour lines, and
may neither cross the others at right angles nor be
parallel with one another, but they may still be
formed in the same manner.
When it comes to flooding, the water may be
taken from the head distributary and sent down first
one tier of checks and then another, dropping the
348 Irrigation and Drainage
water from the first into the second and the second
into the third, over one or more breaks or weirs in
the dividing check ridges. If, however, the checks
are large or very many, this plan will be unneces-
sarily wasteful of water, and a better plan is to take
the water down the crest between two lines of checks
in a secondary furrow. From this furrow the water
may be turned into the check on one side and then
on the other, flooding by pairs down the whole line.
In the San Joaquin valley of California, in Kern
county, there is laid out one of the largest flooding
systems in the world. Here are more than 30,000
acres of alfalfa in a single solid block. The slope of
the couutay ranges from 5 feet to the mile to less
than 2. Large volumes of water are at the command
of the company, — 30 cubic feet per second, — and so
the checks, laid out with their level ridges on contour
lines, have various sizes and many shapes. The
largest checks contain 200 acres, while the average is
about 40. The ridges are 12 to 20 inches high, with
a maximum width at the base of 12 to 18 feet,
broadly rounded, and all covered with the growing
alfalfa.
Where the period of rotation is short, and where
crops not suited to flooding are used in the rotation,
then narrower and temporary check ridges would be
formed for the crops to be watered in this way. The
smallest ridges maj- be rapidly made on recently
plowed fields by using a V - shaped ridging scraper
drawn by horses, with the open side forward. The
spreading wings throw the loose earth into the angle,
I r,i<-
J ^
I -^i
/I
/I
^.
|/ i
D
Fig. 87. Flooding field by reetaugiilar cheeks. (Gninsky.)
Fig. 88. Flooding field by contour checks. (Grunsky.)
350
Irrigation and Drainage
where it is dropped iu a continuous ridge, because a
portion of each plank is cut away at the vertex, thus
leaving an opening which passes over the gathered earth.
If larger ridges are desired, a wider scraper, with wide
opening in the rear, ma}- be followed hy one of
smaller dimensions, to complete the gathering.
The mounted road grader may be used to advan-
tage in forming such ridges, and it would be an easy
matter to construct a special tool for this purpose on
. ^^^-
"---^^:
^^^ ^W
^■H^dK'^^i T M :j '^'m.
^ %~M
wwwm
.. p.
Fig. 89. Model of flooding by checks.
the principle of the road grader, but having two
scrapers instead of one, mounted in such mauner that
they could be set closer together or farther apart, as
desired.
After the earth has been gathered into ridges, this
may be smoothed down and rounded with a light
harrow, followed by a roller, if greater firmness is
desired. In Figs. 87, 88 and 89 are different forms
of flooding checks, showing how the water may be
handled in them.
Fitting the Surface for Irrigation
351
FITTING THE SURFACE FOR IRRIGATION
Whichever system of flooding or other irrigation is
used, it is very important that the smaller inequalities
of the surface should be removed by some method of
grading, in order that the water may spread uni-
formh', wetting the whole area. If this leveling is
not done, some portions of the field will receive too
much water while other areas will receive too little or
none at all, and hence yields far below the maximum
will be the result.
Various forms of leveling devices are in use, and
Fig. 90 represents one of the best, made specially for
this purpose, and an ordinary road grader would un-
questionably form an excellent tool for doing this
work.
There are many forms of scrapers of simple con-
struction which are improvised on the farm to meet
the needs of the moment. One of these is a letter A
form, made of two 2x12-
inch plank, put together
so as to stand on edge
and be drawn over the
ground weighted with
the driver riding upon
it. The lower edges of
the plank may be shod
with strips of steel or
band iron, and thus made more durable and effective.
Another form is represented in Fig. 91, and con-
sists of two side runners held together by cross-bars
Fig. 90. Shuart laud grader.
352
Irrigation and Drainage
of strong plank, set at an angle and shod with steel,
as shown. This tool is much used in France and
Italy, and a modification of it we saw in use at
Grand Junction, Colorado, where a pair of low wheels
13 g
<S'
M'
Fig. 91. Simple land grader.
were attached to the front of the scraper on a bent
iron axle, which could be worked by means of a lever
to raise or lower the scraper at will, thus causing it
to drop or take on dirt where desired.
FIELD IRRIGATION BY FURROWS
Where crops like maize, sorghum and potatoes are
grown in large fields, and where intertillage must be
practiced, it is usually best to irrigate hy the furrow
method after the crop is on the groiind. In countries
Field Irrigation hy Furrows 353
where the soil must be prepared for planting hy first
Avatering, it is very important, especially with pota-
toes, that the soil should be thoroughly saturated to a
depth of 4 feet before fitting the ground.
If these crops are to follow clover or alfalfa, as
will usually be the case, the preliminary watering may
be given in the late winter or early spring by one of
the flooding methods, if the ground has been fitted for
that ; but however the saturation is accomplished, the
soil should have all it will carry at the time of fitting
for seed, unless natural rainfall may be depended
upon .
After planting, frequent surface tillage to conserve
the moisture should be practiced, and the crop carried
forward as far as possible without irrigation. The
harrow should follow the plants* at once for both
maize and potatoes, and frequently thereafter as long
as the crop will bear it without injury, which will be
after both are well out of the ground.
Where a vigorous growth of vines can be main-
tained by intertillage alone until -they cover the
ground and the tubers begin to set, this is by far the
best practice for potatoes. So, too, is it best for
nearly all crops planted in rows which permit of cul-
tivation ; and it should ever be kept in mind that
4 feet of good soil well saturated and well cared for
by intertillage may easily carry 6 and even 8 inches
of available water, and this, under good conditions,
is far more effective than any which may be ap-
plied later.
When potatoes are ready to be laid by, the last
w
354 Irrigation and Drainage
cultivation should be with a double -wing cultivator,
which will form a furrow midway between the rows
and at the same time throw the soil up under the
vines, forming a high, broad ridge of mellow soil
above the roots in which the tubers may set and over
which the water should never rise. The furrows thus
formed fit the field for irrigation.
When the time for irrigation has arrived, which
should be deferred as long as the vines continue to
grow vigorously, water will be taken from the head
ditch and subdivided between as many rows as it wilh
supply, as represented in Figs. 92, 93 and 94, where
the first one shows the canvas dam just put in place
in a head ditch in a field near Greeley, Colorado.
Fig. 93 shows the irrigator, with rubber boots and
spade, opening the head ditch to let t>he water into
the furrows ; while Fig. 94 shows the water 30 minutes
later, as it is flowing between rows 40 rods long.
It will be noted that the water has been let into
only alternate rows, and this is a common practice
where water is scarce. It is also a frequent practice
where water must be taken in rotation and the time
is too short to go over the whole field. In such
cases, when the next turn comes the water would be
sent down the remaining rows.
Very great care is taken not to let in so much
water as to fill the furrows and flood the hills, for
it is far better to let the water rise under the hills
by capillarity.
In another field near the same city, two men were
irrigating 47 acres of potatoes planted in rows 120
Fig. 92. Canvas dam in place, preparatory to turning \yater into
potato rows of Fig. 94.
Fig. 93. Opening bead ditch of Fig. 92, to turn water into rows of Fig. 94.
356 Irrigation and Drainage
rods long and, from a single head ditch, sending the
water the whole length. They were nominally using
175 Colorado inches of water, distributing it in alter-
nate furrows.
Before going home at night they divided this head
between 40 rows which had been once irrigated,
Fig. 91. Irrigating potato rows 40 rod-S long from head ditch of Fig. 92.
gauging the flow in each, so that, in their judgment,
the lower ends of the furrows would be nearly reached
on their return in the morning. After watering once
begins, it is kept up until the crop is matured, going
over the field every 10 to 15 days.
In the growing of potatoes hy irrigation, it is a
matter of the greatest importance that the ground
shall be kept well moistened continuously after the
tubers have .begun to form, so that they shall be kept
Field Irrigation hy Furrows 357
steadily growing. If the ground is allowed to become
dry enough to check their growth and another irri-
gation follows, the tubers will then throw out new
growths and become irregular in form and unsalable.
In Colorado the potatoes are usuall}^ planted in
rows 4 feet apart. This distance is much greater
than is required in humid climates, and it would seem
that were the same amount of seed planted upon
three -fourths of the ground, or even five -eighths,
making the rows 36 inches or 30 inches apart instead
of 48 inches, the ground could be more thoroughly
watered and larger yields per acre secured.
It is certain that the practice of only watering
alternate rows, which is common where water is scarce,
does not permit the largest yields to be secured. It
has been shown by studies in the humid climate of
Wisconsin, and with only 30 inches between the rows,
as a mean of two years' trials, that watering between
all rows gave a yield of 317.3 bushels per acre ;
watering between alternate rows gave 277.1 bushels
per acre, when the natural rainfall alone gave 211.6
bushels per acre. That is to saj', the irrigation
between all rows increased the yield over the natural
rainfall 105.7 bushels per acre, while irrigating between
alternate rows only increased the yield 65.5 bushels
per acre, making a difference between the two methods
of irrigation of 40.2 bushels of merchantable tubers
per acre.
In these experiments the field was divided into alter-
nating groups, which were watered and not watered,
so that there were two rows in each irrigated plot
358 Irrigation and Drainage
watered on but one side, and it was the yield from
these rows which has been used in making the com-
parison.
It was also found that the first row not irrigated
on either side, and hence standing 45 inches from
the center of the water furrow, had its yield increased
by the watering only 7.9 bushels per acre. This
makes it appear that were the potatoes planted in
rows 90 inches apart and the water applied in a single
furrow between each two rows, the benefit derived
from the water would be much less.
It is very clear, therefore, that in furrow irriga-
tion care must be taken that the water is not led
along lines tpo distant from the plants which are
to use it.
Where the water is to be allowed to run some
time in individual rows, and where considerable quan-
tities are being handled, it will often be found desir-
able to take it out of the head ditch into short
feeders which supplj^ a certain number of rows, as
represented in Fig. 95, where the water in the fore-
ground is in the head ditch, the feeder standing next
sending water into 8 rows of rape, 28 inches apart
from center to center, from which the first cutting
has just been removed.
Sugar beets, maize, and all field crops upon which
intertillage is practiced would be irrigated in a similar
manner ; but in such close planting as that above
on sandy loams or lighter soils, it would probably
be sufficient to lead water down every other furrow,
keeping the other rows under frequent flat cultivation.
Field Irrigation by Furrows
359
In Italy, where so much work is done by hand, it
is a frequent practice to throw the field for maize
into flat ridges or beds 6 feet wide with strong irri-
gation furrows between, planting the corn in an
open broadcast manner on the beds, to be watered
Fig. 95. Dividing water between eight rows of recently cut rape.
by flooding through the heavy furrows. -The same
practice is followed to some extent for the small
grains and clover also.
WATER-MEADOWS
Most water-meadows are laid out with the view
of maintaining a continuous flow of water over the
whole surface for considerable periods of time, with
360 Irrigation and Drainage
bat little personal attention. Large volumes of water
are usually used, and in Europe especially this is
applied more extensively out of the growing season
than during it, or, more exactly stated, during times
when the crop is off rather than when on the
ground.
Reference has already been made to the water-
meadows near Salisbury, Euglaud, where Fig. 16
shows a large part of the river Avon diverted into
a canal to be led out for water-meadow irrigation.
In Fig. 96 is represented a diagram of one of these
water-meadows covering about 15 acres. The solid
lines are permanent distributing ditches beginning in
the head distributary and ending near the river at
the foot of the field. They are placed about 3 rods
apart, upon the crests of ridges which are quite
steep, sloping from 1 in 12 to 1 in 15 feet toward
the dotted lines, which are permanent drainage fur-
rows. It is on this field that the photograph shown
in Fig. 17 was taken. In talking with a "mead-
man," whose business is to water one of these meadows,
it appears that water has been run over them year
after year for so long a period that no one knows
who laid them out. The mead -man in question was
past sixty years of age, and both his father and
grandfather had been mead -men for the same field.
It is quite probable, therefore, that the steep slopes
now found have been to a considerable extent a mat-
ter of growth due to deposit of sediments in the
distributaries, and to some extent to erosion along
the drainage lines. The plan of this sj'stem of ii'ri-
Water- Meadows
361
gation is to hold the distributaries along the crests
of the ridges full of water their whole length, so
that it shall overflow from both sides and run down
Fig. 96. Plan of old water-meadow, Salisbury, England.
the slopes into the drainage ditches in a thin and
even veil; and in order that this shall be realized,
the distributaries are widest at the upper end, grow-
362 Irrigation and Drainage
ing gradually narrower toward the foot, while the
drainage ways increase in width toward the foot. In
the meadow in question, the measured widths and
depths of the distributaries at their heads were 42
inches by 24 inches respectively, in all except Nos.
10, 11, 12 and 13, 10 and 11 being 28 by 24, 12
being 48 b}^ 24 inches, and 13 14 inches wide and
12 inches deep ; but the capacity of the drainage
ditches was onl}^ about one -fourth that of the dis-
tributaries.
In Italy the winter meadows, when laid out in
what is regarded as the best manner, have sloping
faces not wider than 25 to 30 feet, and with the crests
12 inches higher than the hollows, while the lengths
are quite variable, depending upon the volume of
water at command, but usually being 8 or 10 times
the width. The distributaries have a width of 12
inches and a depth of 6 to 7 inches, while the drain-
age lines have dimensions about one-half of these.
In the summer water-meadows of Italy, the sur-
face is much more nearly level between the distribu-
taries, and often there is no intermediate drainage
furroAV, its function sometimes being fulfilled by a line
of drainage tile beneath the surface.
In the Campine of Belgium, extensive sandy plains
have been laid out in water-meadows, and Fig. 97
represents a small section of this system near Neer-
pelt, where the water is distributed through canals
on the crests of ridges, as already described, and
in the plan the heavy lines represent the distribu-
taries, while the lighter lines represent the drainage
X
1
1
1
^ — 1
:
D
\
>v
■^
1
1
1
^
J
1
1
1
1
1
' 1
— ^ 1
A
364 Irrigation and Drainage
system. It will be seen that the land is laid out
so as to use the surplus drainage water over again,
by collecting it into a foot ditch which is extended
to a lower level in the field, where it becomes the
head ditch, and discharges its water into another set
of distributaries, as represented in the plan, the over-
Fig. 98. Model of field laid out for water-meadows, with slopes exaggerated.
flow water from the upper section being used upon
the third or lower section. The area shown in the
plan is about 26 acres, the distance between the
distributaries about two rods, and the crests stand
nearly 10 inches above the troughs. In Fig. 98, there
is represented a small piece of ground laid out upon
this plan on a reduced scale.
It will be seen that this system of irrigation not
only involves a large amount of labor to fit the land,
Irrigation of Cranberries 365
but it throws out of use a large percentage of the
area irrigated, while at the same time greatl}^ inter-
fering with the working of the ground and harvesting
of the crops. Evidently the system is not well suited
to American conditions where machinery is to be used.
In the irrigated mountain meadows, such as the
one represented in Fig. 14, the slopes of the fields
are so steep that the water is usually led through
irregular furrows whose direction is determined by
the natural configuration of the ground, and the
practice becomes a species of "wild flooding" where,
on account of the great fall, the water is distrib-
uted without much labor having been expended in
shaping the surface.
IRRIGATION OP CRANBERRIES
Cranberries are usually grown upon very level
lands, where the ground water is naturally at or
very close to the surface. During the growing sea-
son, the aim is to hold the water in the ground to
within 18 or 24 inches of the surface, but on
account of insect ravages and frosts, it is frequently
imperative that the lands shall be flooded quickly
to a depth of 6 to 10 inches, and the water drawn
off again in a short time. To prevent winter-killing,
it is also desirable to flood the vines and hold them
under water until the danger from frost is past in
the spring, and these requirements make it necessary
to have the marshes laid out as represented in Fig.
99, where blocks of land are surrounded by low
366 Irrigation and Drainage
dykes and wide ditehes, and at the same time divided
into narrow lands of 30 to 60 feet by parallel nar-
rower waterways, which are at once distributaries and
drainage ditches, according as water is being applied
or removed. These minor distributaries and drainage
lines are made necessarj- chiefly by the necessity of
rapid and satisfactory drainage after the ground has
Fig. 99. Plan for irrigation of cranberries.
been flooded for protection against insects or frost.
The side ditches may be 3 to 5 feet wide and 2
to 3 feet deep, according to the size of the area
under treatment, while the minor cross -ditches should
be 24 to 30 inches wide and 18 to 24 inches deep.
There are many localities where the land is suit-
able for cranberry culture, but where running water
Irrigation of Graiiberries
367
is not available for the purpose of irrigation. In
some of these localities there are large quantities
of water in the ground beneath the marshes, which
could be utilized if it could be lifted cheapl5^
Where this water need not be lifted more than 10
to 20 feet, and where there is an abundance of it
in the ground, it will often be practicable to lay
n
Fig. 100. Plan for ci-anberry irrigation by pumping.
out a piece of ground in the manner represented in
Fig. 100, with a reservoir in the center capable of
storing water enough to flood the balance of the
ground whenever desired, and then set up a wind-
inill of sufficient capacity to maintain this reservoir
full of water, letting the surplus go to the ditches
if needed there, to hold the water up to the desired
height for best growth.
368 Irrigation and Drainage
The object of placing the reservoir in the center
of the area to be controlled is to utilize the seepage
from the reservoir to hold up the ground water to
the desired level more readily. A 12 -foot steel mill
should readily handle 3 to 5 acres if the water
supply is abundant, the ground not too porous, and
the lift not more than 20 feet. But if by such an
arrangement as this a farmer could have only two
acres or even one acre of cranberries under complete
control as regards frost and insects, as an adjunct to
his general farming, it would net him a handsome
profit which would supplement in an important way
his yearly income.
It would, of course, be necessar}- to be able to
drain the area quicklj^ after flooding, and if facilities
are not the best for this, it would be possible to so
arrange the pump that the water could be thrown
back into the reservoir again, and this could readily
be done for small areas where an engine was used
instead of a windmill for power.
IRRIGATION OF RICE FIELDS
In the irrigation of rice fields, where this is to
be done under the best conditions and where the
highest quality of rice is to be produced, it is a
matter of prime importance that the fields shall be
properly laid out, and that an abundant supply of
suitable water shall be under complete control. It
has been pointed out, in discussing the duty of water
in rice culture, that available statistics make the
Rice Irrigation 369
average amount used equal to a flooding of the field
6 inches in depth once eveiy 10 days, and since so
much water must be used on this crop, the means
for handling it must be constructed with ample pro-
portions.
In South Carolina, at the mouths of the Santee
river, where the natural conditions for rice culture
exist in almost ideal perfection, the fields have been
laid off into flooding basins,, varying in size from
a few acres to thirty and more. Each basin is sur-
rounded bj' a dyke, at the foot of which is a main
distributing ditch 4 to 6 feet wide and 30 to 36
inches deep, much as has been described for cran-
berry irrigation, but on a larger scale, and the
resemblance is made still closer by the division of
the fields into narrow lands 20 feet in width by
parallel ditches 36 inches wide and 36 inches deep,
which are at once the ultimate distributaries and
the drainage channels. Trunks or sluices are pro-
vided controlled by semi-automatic tide gates, which
maj^ be raised at will, on the sea side, to admit
the water to these ditches and flood the fields to
any desired depth, and then closed and the water
retained ; or the gate on the field side may be raised
and the water withdrawn.
After the fields have been plowed and seeded in
the spring, thej- are flooded to a depth of 6 inches
and allowed to so remain until the seed has germi-
nated and the first three roots formed. At this
stage the water is let off for three days to force
rooting, when flooding again occurs to overtop the
370 Irrigation and Drainage
plants and be sure to submerge the highest points
in the field and start the rice there. This done,
the water is drawn to a gauge and changed every
seven daj^s until the stage for dr^- growth has
arrived, after 21 daj^s, or the fifth irrigation.
The water is now held off during 30 days and
the fields are given two dry hoeings. This stirring of
the surface of the rice fields appears to have two
important objects to secure : (1) to destroj^ weeds,
and (2) to so aerate the soil as to admit air to
the roots and to the niter germs for the develop-
ment of nitrates. If the soil is not stirred, the
plants take on a yellow color, which quickly changes
to a dark green after the cultivation, proving this
tillage very important. During this time the dry-
growth roots are formed, which penetrate the soil
sufficiently to enable the plants to stand securely,
while at the same time they absorb the nitrates,
potash, phosphoric acid and other ash ingredients
required to mature the grain.
The cultivation is made more urgent on these
fields because of the fine silt borne in the river
water, which settles and overspreads the surface,
forming so impervious a film that air can only pass
it slowly, and if not broken would set up the pro-
cesses of denitrification, which in turn must cheek
the growth of the crop and cause it to turn j'ellow.
After the dry -growth stage has been passed and
the head is ready to form, the 7 -day irrigations are
resumed and maintained until the crop has been
matured. The frequent irrigations are necessitated
Bice Irrigation 371
because of the tendency of the waters to become
stagnant and poisonous to the rice. So imiiortant is
the complete removal of the stagnant water that pro-
vision is made at the farther corner of each field, by
means of a trunk in the dyke, to permit the water
which has been left standing in the ditches after
draining to be forced out by the incoming water into
another ditch leading to a canal or creek, and careful
watch is kept until the yellow river water has finally
reached the exti'eme corner and forced out all of the
standing water which has been " bagged " in the
ditches.
When the rice crop reaches maturity and is ready
to harvest, a few of the topmost kernels are more
advanced than the balance of the head and certain to
shell and fall upon the field. These tip kernels, too,
are liable to be red, and if allowed to germinate the
next season would mature heads with kernels still
more highly colored, and tend in a short time to
develop the " red rice " which so seriously lowers the
grade and market price.
To avoid the development of red rice on the
marshes, it is the practice, after the harvest has been
removed, to again flood the fields and germinate at
once all of the shelled rice which has fallen upon the
ground, so that the winter frosts shall kill the plants
and thus remove the red rice. It is stated that if the
seed is placed in the ground where it cannot ger-
minate, it may retain its vitality for five years, and
hence where the practice of fall flooding cannot be
resorted to it becomes necessary to adopt some system
372
Irrigation and Drainage
of rotation in rice culture which shall furnish oppor-
tunity for all of the red rice to have been germinated
and killed before another crop is placed upon the
ground, and it is the great ease with which the Caro-
lina planters are able to control this difficulty, and
the gi'eater cost of rotation necessitated by other
Fig. 101. Plan of rice irrigation, as practiced in South Carolina.
conditions, which gives them one of their great
advantages over other rice -growers, enabling them to
command the highest price in the markets of the
world.
The detailed method of handling water on a Caro-
lina rice plantation is represented in Fig. 101, where
eight of the many fields shown in Fig. 67 are
represented enlarged.
Bice Irrigation 373
When the tide falls, the gates on the inner ends of
the trunks aiitomaticalh" close and prevent the escape
of the water during- any desired period, while the
dropping of the outer gates prevents the entrance of
any inore water until they are again raised. To drain
the fields with an outgoing tide, it is only necessary
to lift the inner gates and the work goes forward to
completion without further attention, so that the
handling of the water both ways is extremely simple,
effective, and remarkably cheap.
The irrigation of rice on higher lands more nearly
resembles the irrigation of meadows where flooding in
checks is resorted to, except that here the checks are
filled to a standard gauge with water, and then a slow
stream is kept moving into and out of them as long
as desired, the water usually entering at one corner
and leaving at the diagonally opposite corner. The
dividing ridges which form the checks have a height
of about two feet, and the rice fields are kept under
water until the heads are formed, when the water is
drawn off and let on again at short intervals until the
kernels are well formed, when the water is removed
and the fields allowed to become dry and the grain
mature, preparatory to harvesting,
ORCHARD IRRIGATION
In orchard irrigation, several methods of distribut-
ing w^ater are practiced, but there is none followed
so generally and with so good results as the furrow
method, represented in Fig. 102, where the water is
Orchard Irrigation
375
being led through an orange orchard in an ideal
manner, both as to number and size of furrows and
volume of water which each is permitted to cany.
The aim is to allow small streams to flow slowly
through the narrow furrows for a long time, until the
water has penetrated b}^ percolation deepl}- beneath the
surface and at the same time has spread broadlj' by
Pig. 103. Orchard iiTigation, with wooden fliirne in foreground.
capillarity side wise under the surface mulch. In Fig.
103 is shown a wooden flume box, which brings the
water to the orchard, delivering it to the several
furrows through holes in the side which are X-inch
to 1 inch in diameter, and which are provided with
wooden buttons or metal slides for regulating the
amount of water admitted to each furrow.
The appearance of the furrows after the capillary
spread has been considerable is represented in Fig.
Fig. 104. Capillary spreading of water through soil from water furrows
in p5aeh orchiird, Gi'aiid Junction, Colorado.
Fig. 105. Foot ditch for one orchard and head ditch for lower one.
Orchard Irrigation
sn
104. When the stage of surface wetting shown by
the dark margins of the furrows has been reached,
the water has usually percolated to a depth of three
Fig. 100.
Lower orchard taking water from foot
ditch of Fig. 105.
or more feet, and has at the same time spread later-
ally so as to meet beneath the furrows.
■ Orchards are frequently arranged as represented in
-378
Irrigation and Drainage
Fig. 107. Head ditch or cement flume for orange orcliard,
Redlands, California.
Figs. 105 and 106, so that the surplus water from the
furrows in the upper one is collected in a foot ditch
shown in the center of Fig. 105, and redistributed in
a second set of furrows crossing a lower level, shown
in Fig. 106. The water may be controlled by a simple
gate in a sluice -box, shown at 1, 1 in Figs. 105 and
Orchard Irrigation
379
106, which permits as much water to pass from the
foot ditch into the lower furrows as is desired. This
method of irrigation is always less economical of
water than where the water admitted to each furrow
Fig. 108. Large young orc-hai'd on gravelly flood plain of
Santa Ana river, with cement flume.
is so nicely adjusted that there is no waste into a
foot ditch. So, too, is there less waste land.
Still another method of utilizing the water which
may waste at the foot of the orchard is to have there
a strip of alfalfa, clover or grass to take this surplus
with little or no attention or waste.
380
Irrigation and Drainage
But where cement or wooden distributing flumes,
such as are shown in Figs. 107 and 108, are used,
it is usually quite easy to so completelj^ control the
discharge that no waste need occur, and in eases
where water is scantj^ and expensive this method is
adopted to great advantage.
Fig. 109. Model of orchard irrigation by ring furrows.
When the trees of an orchard are young, it is
quite unnecessary to irrigate the whole ground, and
a common practice is to inake a furrow around each
tree, as represented in Fig. 109, allowing the water
to flow along the single distributing furrow, sending
it into the side rings for 12 or 24 hours until a cone
of saturated soil is secured below each tree. As the
Cultivation After Irrigation 381
trees become older, the encircling furrows may be
made larger, until finally it is better to lead the water
along two single furrows on each side of the row,
as shown in Figs. 104 and 106. With increasing
spread of root, the number of furrows would be
increased until a watering of the whole ground has
become needful.
CULTIVATION AFTER IRRIGATION
A cardinal principle in orchard irrigation should
ever be thorough, deep saturation, followed, as soon
as the soil will permit, with thorough cultivation, fre-
quentlj' repeated. In Fig. 110 is represented an excel-
lent mulch-producing tool for orchard work. It is
drawn by three horses ; can be set to run at any
depth ; makes a clean cut of the whole soil without
bringing the moist portion to the surface, and is
provided with a steering wheel, which permits the
driver to easily throw one end of the long cutting
blade quickly and accurately to one side and bring it
close to the trunk of a tree without driving the team
near enough to endanger either the trunk or limbs.
As the blade of the tool is 8 feet long, the orchard
may be covered quickly with it. Smaller sizes, with
5 -foot blades, are also on the market in California.
Another form of orchard cultivator to which fur-
row plows may be attached is represented in Fig. 111.
Ordinary forms of cultivators must necessarily tend
more to invert the soil and bring the wet portions to
the air, and thus be less economical of moisture. They
jP^
• .A
.. ■■ ■■•■■ in'.'. .-■■ ...
Sg;^^:.:;,
E^K'- V
■»■ ^^' -^
^'H-*^§^*'^'-;i^faH
^V^rii'
■~ •^'^"•" —
Fig. 110. Three-horse orchard cultivator used at San Jose, California.
Fig. 111. Combined orchard cultivator and fxirrowing tool.
Cultivation After Irrigation 383
have, however, advantages over the other form for
going over the ground the first time after irrigation,
when it is important to break the moist soil into a
crumbled condition.
Systems of flooding are also adopted in orchard
irrigation, sometimes flooding the whole ground or
small checks surrounding the trees, when these are
young and the water scanty, but this method is far
more wasteful of water and much more injurious to
the texture of the soil, unless it is sandy. When
following it, care must be taken to prevent water from
coming against the trunks of the trees and stand-
ing there.
In humid climates, on lands where the soil will
not wash badly, the methods of orchard cultivation
practiced in the west would give far better results
than leaving them so persistently in grass, as is the
more common practice. The moisture of the soil
should be saved for the trees as a rule, rather than
used for any other crop after the trees become large.
SMALL -FRUIT IRRIGATION
In the irrigation of strawberries, raspberries, black-
berries, and similar fruits, the furrow method will
almost always be practiced, leading a slender stream
along each side of the row and quite close to it.
Blackberry and raspberry roots penetrate to a suf-
ficient depth to permit a thorough saturation of the
soil and good cultivation before the berries are ready
to pick, so that no irrigation will be required during
384 Irrigation and Drainage
the picking. Strawberries, however, are so shallow-
rooted that water enough cannot be placed within
reach of the plants to make irrigation during the
picking season unnecessary. It is, therefore, a com-
mon practice to lay out strawberry fields in such a
way that the water inay be led onlj^ between alternate
matted rows in deep broad furrows, holding the water
well up the sides so that it may better spread laterally
under the plants. This practice, although not as
economical of water as irrigating between every row,
has the advantage of not seriously interfering with
picking, there being alwaj's sufficiently firm ground
upon which to walk.
GARDEN IRRIGATION
Garden vegetables are oftenest raised in beds and
patches of such small dimensions, and on soils so
light and open, that the irrigation of them is accom-
plished most readih" by methods closely allied to those
of flooding. A relatively large volume of water is
quickly brought to the point needed and applied all
at once, and without waiting for either percolation or
capillary spreading to take place,
A method represented in Fig. 112 consists in lay-
ing the ground off into beds, and getting the seed
planted, when the surface is overspread with a thin
dressing of rather coarse litter or horse manure.
Water is turned into the head ditch, which is
choked with a little soil or an irrigator's broad
hoe set so as to turn the stream between the
Garden Irrigation
385
beds, when the irrigator dams the current at his feet
with a gunny sack and with a long- handled basin
dextrously bales the M^ater out as rapidly as it reaches
him, dashing it over
Fig. 112. Diagram of garden beds.
the littered surface
until, in his judgment,
water enough has been
applied. The dam is
then moved and a
second area irrigated,
the operation being
repeated until the
ends of the beds have
been reached, when the head ditch is opened and
closed in another place, turning the water in between
other beds.
When the water has had time to penetrate the
soil, when the surface is beyond danger of crusting,
and the delicate plants have begun to emerge from
the ground, the litter may be raked off. In this
manner a man was observed to irrigate an area 33
feet by 150 feet in one hour, using the water which
could flow through a short 3-inch pipe, filling it half
full, and Fig. 112 is a diagram of the beds, 15 feet
wide between the waterways.
Another type of irrigation is shown in Fig. 113,
where the garden is ridged and furrowed every 18
inches. Celery is planted on one side of each ridge
and lettuce on the other. When irrigation is required
the furrows, 6 inches deep, are flooded one at a time
from a stream led along their head, and these, when
Y
386
Irriffdfio}) and Drainar/e
.^^KBeir
i'ig. 113. Furrow flooding in gaideu.
quickly- filled, are supposed to hold sufficient water
for one irrigation, enough to cover the whole ground
2.5 to 3 inches. In Fig. 114 is represented a cross
section of the rows.
In still other cases shallow basins are formed
about each row of plants, as represented in Fig. 115,
where cabbages have been set. It will be noted that
the basins are not only narrow but short, so that
each maj' be quickly filled,
one after another, from a
p.^..-r..-.. ...,:i.;.fuv.,..:..^^.i^-5v.v;^;.,yv;„,v. gj.j.ggjj^ jg^j aloug au allcy
Fig. 114. Diagram of section of rows bctWCen twO SetS. As the
and furrows in Fig. 113. i j_ i i ,■■
plants become larger the
ridges are gradually cut down to hill the plants, and
thus form water furrows in their stead. This is one
Garden Irriyafion
387
method, as practiced by the Italian gardeners, both
in their native country and on the sandy lands at
Ocean View, south of San Francisco.
In Fig. 116 is shown another cabbage field recently
transplanted by the Chinese gardeners at San Ber-
nardino, Cal. In this case the field is quickly and
roughly -ridged and then the large plants hastily set
low down in one side of the ridge. After irrigation,
and wheu the water has settled away so as to permit
working, a little soil from the ridge is pulled about
the plants, as seen in the cut. In time the whole
ridge has been pulled over, leaving the plants stand-
ing in the center of the crest.
The French about Paris throw their fields into
broad double ridges, wide enough to carry two rows
Fig. 115. Basin flooding of cabbage in garden of sandy soU.
388
Irrigation (Oid Drainage
of vegetables 24 inches apart, and these are sepa-
rated by furrows a foot wide and 6 inches deep,
through which water is led for irrigation, and Fig.
117 is a plan of a section of the upper end of a cab-
bage field as laid out on the valley sands of the river
Seine, just outside the city walls.
Fig. 116. Chinese method of irrigating f-ahbage,
San Bernardino, California.
Melons and cucumbers are planted upon still
broader beds, 6 to 8 feet wide, separated by water
furrows, as represented in Fig. 118, the hills being
planted near each margin of the bed and the vines
trained away from the furrows.
At Rocky Ford, Colorado, where melons are raised
Garden Irrigation
389
on a large scale, fields are furrowed every 6 feet
with a double shovel plow. The seeds are planted
ill the edge of the ridge away from the furrows, and
the soil watered through the furrow only, by lateral
capillary flow, great care being taken to avoid flood-
ing the surface. Cultivation follows each irrigation
after the plants are up until the vines become too
large, but watering must be kept up about once in
ten daj's until the crop is mature.
Fig. 117. Diagram of cabbage irrigation at Gennevilliers, near Paris.
Another system of irrigating gardens is repre-
sented in Fig. 119, where the rows are hilled, leav-
ing shallow furrows between them, but arranged so
that a stream of water can be led across the ends
and turned into them one by one. The water is led
to the lower rows down the middle furrow, and with
a broad irrigating hoe, having a blade 12 inches
390
Irrigation and Drainage
|Fig. 118. Irrigation of melons and cucumbers by Chinese at San Bernardino.
long and 10 inches deep, the soil at 1 is quickly
turned over to 2, to form a dam in the stream,
thus allowing the water to flow between the two
lower rows until that furrow has been filled to a
sufficient height. The soil from 3 is then turned
over to 1, thus closing 1 and allowing the water to
enter 3. When 3 is full the soil from 4 is brought
back to 5, which turns the stream in there. When
4 has received enough, the water is turned into 6
by moving the soil from there to 4. In this manner
the irrigator advances from row to row until both
sides of the whole bed have been watered.
In other cases, small or large areas of garden
plants are enclosed in small, shallow basins by throw-
Garden Irrigation
391
ing up minute dyke -like ridges not more than 6
inches wide and 4 high. These basins may be
arranged in a single or double chain, and the water
led down one side or between them. In this case,
again, the watering would usually begin at the lower
end, and with the hoe a section of the border of a
basin would be drawn out to act as a dam across
the stream, as shown in Fig. 120. The soil from 1
Fig. 119. Plan of furrow garden flooding by successive rows.
and 2 would be drawn around to 3, thus turning
the water into both beds. When these were watered,
the soil from 4 and 5 would be drawn around to
6, and the next two beds irrigated. In this manner
the gardener advances rapidly from bed to bed with
but little trouble and labor.
THE IRRIGATION OF LAWNS AND PARKS
It should ever be kept in mind, where shrubbery,
trees and grass are grown together, as is so com-
892
Irrigation and Drainage
monly the practice in humid climates, that two crops
are being grown at the same time upon the kind, and
that under these conditions more water is demanded.
The roots of shrubs and trees are more deeply placed
in the subsail than are most of those which feed the
lawn grass, and hence all rains too light to over-
saturate the surface 6 inches are practicalh' secured
by the grass, and since to maintain a good lawn
! , « 4
Fig. 120. Plan of basin flooding in garden irrigation.
requires more water than ordinarily falls as rain,
even in quite humid climates, it follows that in all
public parks, cemeteries and ornamental grounds about
homes, there should be provided an abundant supplj''
of water for thorough irrigation.
In watering lawns and parks, so much water is
demanded that it ought usually to be applied by
some flooding system rather than by spraying, as
Lawn and Park Irrigation 393
is so commonly the practice. The truth of this
statement will be readilj- appreciated when it is
observed that in order to saturate good lawns snffi-
ciently to force any water down where it will become
available to the roots of trees and shrubbery, the
ground must receive not less than 2 to 3 inches iu
depth of water. But to apply this amount with
spraying nozzles is impracticable.
If public parks and cemeteries were more gen-
erally laid out with a view to thorough irrigation
as a part of their proper care all through the cen-
tral and eastern United States, not only would the
growth of shrubbery and trees be far more luxuriant
and satisfactory, but drj^ seasons would not destroy
the many beautiful trees which so often succumb to
drought just in their prime.
Wherever a good well can be had with abundance
of water and a lift not to exceed 50 feet, a lawn of
half an acre, with its shrubbery, together with a
vegetable garden or fruit orchard of several acres,
may easily be irrigated with a plant not costing
more than $300 to $500. Such a plant is repre-
sented in Figs. 121 and 122. This, including well-
house, 2% horse -power gasoline engine and double-
acting pump, having a capacity of 80 gallons per
minute, with over 1,000 feet of 2-inch distributing
pipe and hose, cost, when put in place ready for
work, $440.
In the portion of this plant shown in Fig. 122,
part of the 2 -inch iron distributing pipe for the
lawn and garden, as represented at B, C and D,
394
Irrigation and Drainage
are tapped exery 3 feet for short half -inch nipples
with caps. With this arraugement it is easy to
take out water at auj- desh'ed place, pressure being
Mm
^S^^
m^^^Klk^^iLMii^^
^^Hf^-^''-'
^ m^^:--
^Hv.
■ %#;*ifrr*;:-'.
■g^H
•f ^'-jfe '■
''' - ^ Wi'i'i 1 iw 1 *
"pM ^i ..,
' ^^^^Bk-
* ''j'»^^-
_'
Fig. 121. Small gasoline pumping plant for garden and lawn irrigation.
maintained in the whole system of pipes when the
pnmp is at work. The pipes for watering the lawn
are sunk just flush with the sod, and the nipples
rise obliquely upward so short a distance as not to
interfere with the lawn mower. The arrows show
both the slope of the lawn and the way the water
is distributed. By opening only 7 to 10 nipples at
a time, a large volume of water is secured, which
spreads readily over the surface. In the garden irri-
gation, 15 or 20 rows may be watered at once, and if
Laivn and Park Irrigation
395
a particular stream is a little too strong, this may
be regulated by tlirustiug a bit of stick into the
uipple. For watering beds about the house, four of
Fig. 122. Plan of lawn and garden irrigation.
the nipples are made for attaching a garden hose,
which may also be used to wash windows or a car-
riage. Altogether, this arrangement is very simple
and satisfactory for a suburban or country home,
396 Irrigation and Drainage
and would answer admirablj' for a small market-
garden, where vegetables and fruits are raised.
SUB -IRRIGATION
This method of applying water consists in plac-
ing lines of tile or perforated pipe varying dis-
tances below the surface of the soil, and distributing
water through these instead of in furrows or by
methods of flooding. This system of irrigation
quickly suggests itself to most thoughtful men when
they first begin to handle water for irrigation, on
account of the many difficulties and inconveniences
which are associated with surface watering ; but there
are several very fundamental objections to it which
have usually' led to its abandonment sooner or later
in nearly every place where tried.
Were it not for the objections just referred to,
sub -irrigation would constitute an ideal method of
applying water, and would be universally practiced.
Could it be used, much of the expense of fitting
the surface would be avoided ; the fields would be
almost wholly unobstructed ; all of the ultimate dis-
tributaries would become permanent improvements ;
the surface of the soil could not become puddled ;
mulches developed would not be periodically destroj'ed,
and the duty of water would be vastly increased.
Indeed, so many things appear to be in favor of the
method that it is only with great reluctance that it is
abandoned.
The most insuperable difficult^' with sub -irrigation
Stib- Irrigation 397
is that of applj'ing- sufficient water to thoroughly wet
the surface, aud yet those who have not tried the
plan feel confident that there will be a great saving
in this direction ; but the rate of capillary movement
of water in soil is relatively so slow, and percolation
so rapid in most cases, that it becomes nearly imper-
ative that water shall be placed upon the surface,
where it is most needed aud is of greatest service.
It has been shown under furrow irrigation, where
the water is applied at the surface, that the streams
must usually be led as close as every four feet, to wet
the whole ground, and from this it follows that lines
of tile laid even closer than this would be required
in sub -irrigation. In Fig. 123 is shown the wetting
of the surface which occurred by distributing the
water tlu-ough 3 -inch tile placed 18 inches below the
surface, in which hydrostatic pressure was maintained
sufficient to cause the water to rise one or two inches
above the top of the ground. In this experiment
the tile were arranged as represented at D, Fig.
124, 10 feet apart, and it will be seen that only
about 3 feet in width above each line of tile has been
wet, and yet water enough has been applied to cover
the area more than 6 inches deep. Even at C, Fig.
124, where the tile are only 5 feet apart, it was
necessary to apply 19.68 inches of water in depth to
completely wet the surface, but in this case the sub-
soil was more open than it was at D. It is plain,
therefore, that in order to thoroughly wet the sur-
face of the ground by sub -irrigation, much more
water will be required than by furrow irrigation,
398
Irrigation and Drainage
unless the tile are as close as 4 feet apart and very
near the surface.
The second great o}3stacle in applying sub-irriga-
tion is the expense required to purchase and place the
necessary lines of tile. In watering strawberries,
l-l-i. Difficulty of wetting surface soil by sub-irrigation.
blackberries, raspberries, and other small fruits, one
line of tile would be required under each row. For
orchard irrigation, two lines of tile would be needed,
one on each side of the row when the trees are small,
and the numlier would have to be increased as the
trees reached maturity, until there was at least one
every 5 feet. For general field crops, the number of
Sub- Irrigation
399
tile could scarcely be less thau one line every 5 feet,
and it would be necessary to place them at least far
enough below the surface not to be disturbed in
working the soil in crop rotation.
Fig. 124. Plan of fields for sub-irrigation experiments.
At one cent per foot for 3 -inch drain tile, the cost
for pipe alone would be $87.12 per acre where the
lines are laid 5 feet apart. In addition to this ex-
pense, there would be the cost of transportation,
breakage, and laying of tile connecting with the head
400 Irrigation and Drainage
ditch, and maiutenance, which, in the aggregate,
could not be less than $12.88 per acre when done on
a large scale and under the most favorable conditions,
or a total cost of $100 per acre, at the very best
figure which could be hoped for.
Only in tho.se cases where tile could be placed
barely below the snrface could there be as high a
duty of water as with fuiTOw irrigation, and hence,
where water is high and labor cheap, the cost of water
would decide against sub -irrigation.
Where a field has been uuderdrained, as repre-
sented in Fig. 124, in the lower lefthand corner, it is
easy to introduce the irrigation water at the upper
end of the main, as shown at F, and allow it to set
back through the laterals. By forcing the water in
the main to rise to the surface of the ground at G,
H and A before passing on to lower levels, the
water in all the tile would be placed under pressure
which would force it to the top of the ground with-
out waiting for capillarity to bring it there. In
this manner if the field were underlaid by sand at the
level of the tile, the whole area may be quickly
watered, provided the main has capacity sufficient to
deliver the water to all the laterals as rapidly as
percolation can take place from them. With the
outlet of the tile at E closed and water admitted to
the main at both F and A, the 7,022 feet of tile took
water at the rate of 48 cubic feet per minute under
the 5 acres, or at the rate of 5 gallons per 100 i*un-
ning feet of tile where these were placed in sand 33
feet apart. During the ii-rigation, water was brought
Stib - Irrigation 401
to the surface along most of the lines of tile, as
represented by the dotted area below A. To do this
work, 5.8 inches of water on the level were required,
but it is quite certain that half this amount applied
at the surface in the proper manner would have ren-
dered as much service. The time required to apply
the water at the surface would have been about the
same, but an extra man would have been needed to
distribute it, and the furrows would have to be made,
so that there is this labor to be offset by the cost
of the extra amount of water required for the sub-
irrigation.
But it must be kept in mind that had the field
not been underlaid by sand and the ground water
surface near the level of the tile, and had the pressure
not been held up so as to force the water to rise to
the surface, these results could not have been attained
with tile placed as far apart as 33 feet. The applica-
tion of sub -irrigation to tile -drained areas cannot,
therefore, be regarded as the best method of watering
in any but special cases.
It is quite probable that were this system of
irrigation to be applied to water-meadows to avoid
surface ditches, or even to orchards and small fruits,
there might be experienced difficulties arising from
the tile becoming clogged, either from sediments
moved by the water or by the growth of roots into
the lines of tile.
When the difficulties which have been pointed out
as standing in the way of sub -irrigation are con-
sidered, and when it is recalled that nitrification in
402 Irrigation and Drainage
most soils can take place only near the surface, when
roots are better aerated there, and when here alone
can germination occur, it seems plain that there can
be little reason to hope much from this method of
applying water.
CHAPTER XI
SEWAGE IRRIGATION
The methods of distributing water in sewage irri-
gation are essentially the same as those already de-
scribed. The topography of the field to be watered
and the character of the soil or of the crop, will
determine which method shall be employed. It re-
mains here to state, from the agricultural side of the
subject, under what conditions sewage irrigation may
be practiced to advantage and what crops are best
suited to utilize the water.
OBJECTS SOUGHT IN SEWAGE IRRIGATION
There are two main objects sought in the use of sewage
in irrigation. The first and primary one is to oxidize and
render innocuous the organic matter which it contains. The
secondary object is to vitilize this organic matter, together with
the water and otlaer fertilizers which it may contain, in the
production of crops. Eeference has already been made to this
point in connection with the Craigentinny Meadows, where a
poor soil has been made to yield a gi'oss income of $75 to
more than $100 per acre per annum for nearly a century.
The oxidation and denitrification of the organic matter borne
in the sewage water must be accomplished largely, if not wholly,
through the agency of fermenting germs, and this being true,
it is imperative that the methods of treatment shall be favor-
able to the activity of these forms of life.
(403)
404 Irrigation and Drainage
CLIMATIC CONDITIONS FAVORABLE TO SEWAGE
IRRIGATION
Since the fermentive processes which convert organic matter
either into nitric acid, which is the nitrogen supply for most
cultivated crops, or into free nitrogen gas can take place rap-
idly only under temperatures above 50° F., it follows that sewage
iiTigation is best suited to warm climates, where crops may
be grown the year round, and where the fermentive processes
will be least checked by frosts. In tropical and semi-tropical
climates, therefore, sewage disposal by surface irrigation may
best be practiced when other needful conditions are also favor-
able.
In cold climates, like those of the northern United States
and Canada, where the ground is frozen during five months or
more of each year, it is plain that only about one-half of the
sewage water can be used in crop production, and that during
only about one-half of the year can there be much oxidation
and denitrification of organic matter. Under these conditions,
therefore, if water is applied to land one -half of it must be
filtered by the soil without the concurrent purification which
results from fermentation, and this being true, there can be
only so much of purification as naturally results from the
physical filtration and such chemical fixation as the soil may be
capable of accomplishing.
It is true that the purification of sewage resulting from
filtration through soil is very considerable, so that if isolated
lands of sufficient area are selected for this purpose, the organic
impurities reaching the ground water will be greatly reduced.
It is also true that in cold climates fields to which no sewage
has been applied during the warm season may be reserved
specially for the reception of it during the winter. - These soils
would, therefore, be comparatively dry and capable of receiving
6 to 12 inches of water and of retaining it by capillarity
until warm weather could subject it to organic purification,
and when crops could also be made to utilize the nitrates
developed and other fertilizers brought by the water,
Sewage Purification 405
To handle the sewage in this manner, it would be needful
to bring it to the fields in underground conduits, and to have
the lands laid out for flooding in checks of suitable size, sur-
rounded by barriers of the desired height, but the great diflS.-
culty to be met is the amount of land needful for such a
system. Allowing 50 gallons of sewage per day per person,
a city of 30,000 would require 828 acres to receive the sewage
during 180 days if each check were to be flooded to a depth
of 12 inches.
THE PROCESS OF SEWAGE PURIFICATION BY IRRI-
GATION OR INTERMITTENT FILTRATION
The extremely careful and extended investigations con-
ducted by the State Board of Health at Lawrence, Mass., begun
in 1888 and still in progress, have shown that the purifying
of sewage as it passes slowly over the surface of sand grains
freely exposed to contained air, is the result of bacterial growth,
and that when these germs are not present the sewage comes
through the filter as impure as it went in so far as its dangerous
nitrogen compounds are concerned. But if it is allowed to
pass through slowly enough in the presence of an abundance
of air, the water emerges with so nearly all the nitrogen com-
pounds converted into nitrates that it is as free from them
as the purest spring water.
The essential condition is that an inch or two of water
shall be spread out over the surface of the soil grains in
enough of the upper soil, where free oxygen may gain access
to the colonies of niter-forming germs which multiply there
and feed upon the organic nitrogen in the water, if only
there is an abundance of free oxygen to meet their other
needs. When a new quantity of water is added to the soil,
the purified layer is swept downward by the new supph',
which at the same time drags in after it a fresh supply of
air, and thus the work goes on.
If the sewage water is added too rapidly, before the germs
406 Irrigation and Drainage
have completely used up the organic nitrogen, then it will be
only partly purified ; or if the flow over the field is made con-
tinuous, then the supply of oxygen in the soil becomes so
small that the germs are unable to carry forward the work,
and organic nitrogen passes through largely unchanged and
liable to become the food in drinking water of other but
dangerous forms.
SOILS BEST SUITED TO SEWAGE IRRIGATION
In humid climates, where the rainfall is both frequent
and abundant, the lighter loams and sandy soils are best
suited to this type of irrigation, because upon them there is less
danger of water-logging. It should be understood, however,
that from the agricultural standpoint sewage may be applied
to any soil, provided it is not used in too large quantities or too
continuously ; but as the sandy soils are usually more in need
of artificial fertilization, and at the same time likely to be
deficient in water, they are preeminently suited to this use, and
will usually be chosen by city authorities when they are avail-
able, but simply because a smaller number of acres will answer
the purpose and the cost of the plant be less.
The agricultural value of sewage when properly applied to
land has been so thoroughly demonstrated under so many condi-
tions of soil and climate that there can no longer be any doubt as
to the desirability of its use if the expense of getting it to the
land were eliminated, and it would appear that lands enough in
the vicinity of most cities could profitably receive and use the
sewage if only it were led to them.
DESIRABILITY OP WIDER AGRICULTURAL USE OF
SEWAGE IN IRRIGATION
In countries like Italy, where there are extensive canal
systems largely used for irrigation, it would appear that sewage
disposal by irrigation should become the general practice, pro-
Agricultural Use of Sewage *
407
vided the canals are carrying constantly a sufficient volume of
water to make the needful dilution. The disposal of the sewage
of the city of Milan in this manner has already been referred to
as extremely satisfactory from the agricultural point of view.
In speaking of the opportunities for and the desirability of
improving sandy lands in various parts of the eastern United
States and in the South by silting, it was pointed out that many
Pig. 125. Instruction of praetical gardeners in garden irrigation.
hundreds of square miles of now nearly worthless lands could be
reclaimed by methods of irrigation, and wherever this shall be
undertaken the disposal of the sewage of the same sections
through the canal waters could not fail to be of great advantage
to the lands when applied either in winter or in summer.
Outside the walls of the city of Paris, on the once nearly
worthless gravelly sands of the Seine, is located a garden whose
sign is represented in Fig. 12.5, where, in the midst of a district
408
Irrigation and Drainage
devoted to sewage irrigation, an effort is being made to teach in
a concrete way how thoroughly purified sewage water may be
made by irrigation, and what luxuriant growths may spring fi-om
nearly sterile sands. Fig. 126 is a view within the garden,
where grapes are gi-owing on the left, with dwarf pears and
apples on the right, while in the center is a trench of water
cress grown for market in filtered sewage, the trench being at
the foot of one of the drainage lines leading the filtered water
Fig. 126. Sewage irrigation, model garden, Paris.
to the Seine. So clear was this water that it had the sparkling
brilliancy of that from the purest springs, and outside the
garden women and children came with their buckets and filled
them for use at home. Inside, the superintendent keeps a glass,
and insists that every visitor shall taste and convince himself
how sweet and ptire the water is. Here and further out, at
Gennevilliers, the lands are laid out and divided much like
village lots, where homes, with their vegetable, fruit and flower
Sewage for Garden Irrigation 409
gardens, are being established, and sewage water was handled
there in 1895 by small gardeners with great skill and profit.
The lands are held at $1,000 per acre, and rent at a high price.
The sewage for irrigation is carried beneath the surface in
closed pipes, which are provided with a system of hydrants for
taking out the water where needed, and Fig. 127 shows one of
these, while Fig. 128 is taken at the same place, standing at
the hydrant and looking down the open ditch leading the
water to gardens and orchards, where it is to be used.
Flowers, garden vegetables and fruits were growing upon these
grounds in great luxuriance for the city markets. If such
results as these can be secured in France, why should not the
philanthropic zeal of Greater New York join with the capital
of that city and lead a portion of the water of the higher
lands, together with the sewage of the inland towns and cities,
which is now polluting the streams, down upon the flat New
Jersey sands and convert them into gardens of industry and
plenty, where the unfortunate mothers, with their children now
in the dark streets, could be helped to comfortable homes sur-
rounded by conditions which make physical, intellectual and
moral growth possible.
CROPS SUITED TO SEWAGE IRRIGATION
There is no crop more generally grown on sewage farms
than grass, which is fed green, as cited in the cities of Leith
and Edinburgh and at Milan ; as silage, as has been done at
Croyden and Nottingham, or made into hay, as at Preston. At
Blackburn and at Croyden, also, the lands are extensively pas-
tured, at the latter place by coach and draft horses of the city
for a season, to allow their feet to recover from the jar and
shock of stone pavements.
In England and in Italy very heavy crops of grass are
grown, yielding all the way from 40 to 70 tons per acre per
season. The grass most extensively grown in Europe is the
Italian Rye Grass, but it is not permanent, and the land must
be plowed and reseeded every three or four years if heavy
Fig. 12,. Sewage liydrant at Genuevillier.^
1
1
^:;^>3^^ff
M
%. ;
i
Fig. 128. Stone distributing caual leading from hydrant in Fig. 127.
Crops for Sewage Irrigation 411
yields are desired. On the Craigentinny Meadows, most of the
grasses are the native forms, which soon crowd out the Rye
Grass if it is not reseeded.
Both oats and wheat are extensively grown on sewage
land, but in these cases the land is usually only irrigated dur-
ing the winter. Potatoes, turnips and mangels, as well as
cabbage and cauliflower, are also grown.
At Croyden and Preston, potatoes are grown on a large
scale on winter irrigated land and the crop sold at auction
when mature at $60 to $75 per acre, the purchaser digging the
potatoes. Fig. 129 shows a crop of early potatoes grown at
Croyden which sold in July for £15 per acre, and Fig. 130 is
a view of the cement ditch in which the water is brought to
the fields from the city. When summer irrigation of potatoes
is i)racticed at Croyden, the superintendent stated that he pre-
ferred to use the water only after it had drained from another
field. He also stated that he thought the sewage water tended
to intensify the scab.
At Nottingham, where much wheat is raised, this is grown
on winter irrigated land, but cabbage, turnips and mangels are
irrigated in the summer as well as winter. The cabbages
raised here 'are the large stock varieties, planted in rows 4
feet apart with the plants 3 feet apart in the row, and
enormous yields are secured of the vegetables named and fed
to a herd of from 800 to 1,000 cows.
At Gennevilliers, nearly all varieties of garden truck were
being raised with great success, and there were orchards of
pears, prunes and apples, and vineyards of grapes, heavily
loaded with fruit in August of 1895. So, too, at Berlin,
mangels, turnips, celery, onions, parsnips, beans, cabbage and
cauliflower were raised on their sewage farms.
While the general practice in Europe seems to be to favor
summer irrigation of grass, and winter irrigation for small
grains and cultivated crops generally, it appears clear that
there are few if any crops to which sewage may not be applied
with great advantage if only rational practice is followed.
It will be readily understood that where fertilization is the
^J^r^i^« '•«.
Fig. 129. Harvesting early potatoes on Croyden sewage farm, England.
Fig. 130. Cement canal at sewage farm, Croyden, England.
Sewage Irrigation and Healthfulness 413
main object, together with the disposal of the sewage, lands
may be irrigated at once after the removal of a crop, such as
wheat or any of the small grains, so that there may be ample
latitude for distributing the water at almost any season of
the year.
In climates where the winters are severe, it is necessary to
apply the sewage to land not in grass or other perennial crop,
as the freezing of thick coats of ice over the meadows is quite
certain to greatly injure if not kill the grass. Another point
which the agriculturist should keep in mind and guard against,
is the application of sewage to crops in too concentrated a form,
and especially should it be so much diluted or strained that the
sludge will not collect upon the sui-faee in sufficient quantity
to close up the pores of the soil and interfere with proper
aeration.
INFLUENCE OF SEWAGE IRRIGATION UPON
THE HEALTH
Reference has been made to experiments and observations
which show that the feeding of grass from sewage farms to
milch cows produces no injurious effects upon the milk itself.
The late Colonel Waring states that the health of the people
living upon the sewage lands at Gennevilliers is generally excel-
lent, and that "even in 1882, when there was a cruel epidemic
of typhoid fever in Paris, there was none here." He further
says : " If there is still room for doubt on any point, it is as
to the character of the few bacteria which escape the action of
the process employed, and are found in the effluent. It is not
known that disease germs exist among these, and it is altogether
probable that they do not. So far as these organisms are
understood, it is thought that they cannot withstand the
destructive activity of the oxidizing and nitrifying organisms
which are always present, and it is believed that only these
hardier organisms exist in the effluent of land -purification works.
Certain it is that no instance has been reported where con-
tagion was carried by such effluents, and experience at Genne-
414 Irrigation and Drainage
villiers has shown that typhoid fever and cholera, when rife in
Paris, were completely arrested at the irrigation fields."
" In the Massachusetts table of comparison of the purified
eflluent of seven sewage filters and the waters of seven wells
used for drinking by many persons, it is shown that there
were three and one-half times as many bacteria in the well
waters as in the effluents."
Pakt II
FARM DRAINAGE
CHAPTER XII
PRINCIPLES OF DRAIN AGE
It has been pointed out that if all of the irri-
gated lands of the world were brought together in
a solid body, they would scarcely aggregate more than
an area 500 miles on a side, or 250,000 square miles.
But Professor Shaler estimates that in the United States
alone, east of the 100th meridian, there are more
than 100,000 square miles of swamp lands. Some of
these have been reclaimed by drainage, and the great
majority of them could be, if the expense of the
reclamation would be warranted by the returns which
would follow. In the Canadas, in Europe, and in
other portions of the world, also, there are vast areas
of land, when measured in the aggregate, which
must be drained before they can become agricul-
turally productive. Hence the principles of land drain-
age, like those of irrigation, must be clearly under-
stood by those who are concerning themselves with
(415)
416 Irrigation and Drainage
the great world problems of better homes and all
which these mean.
Further than this, on account of the fact that a
large majority of swamp lands and lands which may-
be improved by drainage are not massed together, but
are scattered broadly in small tracts, so related to
the higher and better -drained lands that these must
often be improved in order to work the others to
the best advantage, the principles of farm drainage
become a matter of great importance to a large pro-
portion of the rural population, and through good
roads to the people of cities as well.
THE NECESSITY FOR DRAINAGE
The first and most fundamental necessity for land
drainage, as has been pointed out in discussing
alkali soils, is the removal of the more soluble salts
formed by the decay of rock and organic matter,
because too strong a solution of salts in the soil water
is fatal to the growth of vegetation, and gives rise
to the alkali lands. So long as there is sufficient
leaching to hold the soluble salts down to small per-
centages, so that neither plasmolytic nor toxic effects
result, then the first imperative demand for thor-
ough drainage in all soils is met,
The second imperative demand for drainage is to
prevent a stagnation of the soil water, which means,
to avoid the exhaustion of oxygen from the air in
the soil water and in the spaces not occupied by
water, because an abundance of free oxygen in the
Necessity for Drainage 417
soil is a fundamental necessity to plant life, and
thorough drainage secures this.
The third demand for drainage is to render the
soil sufficiently firm and solid to permit the field or
road to be moved over without difficulty or incon-
venience. If the spaces between the soil grains are
completely filled with water, then there is no surface
tension, and so only a slight friction to bind the
grains together, and hence they move so easily upon
one another as to be unable to sustain much weight,
and the horse or wagon mires.
Everj'one is familiar with the hard surface pos-
sessed by wet beach sand, from which the water has
just withdrawn, and how yielding it is when under
water and also when it becomes dry. In the first
case, the sand grains are bound together by the thin
films of water which surround them ; in the second
case, there is no free water surface between the grains,
and the sand tends simply to float and so moves
easily ; while in the third case, when the sand is
dry, the binding water films have either drained
away or have been lost by evaporation, hence there
is nothing to hold the grains together.
The hard, firm character of a clay soil when it
loses its moisture is due to the fact that the grains
are so small and so close together that the little
material which is held in solution in the soil water
cements them together when dry. Were the grains
large like those of the sands, with few of the fine
particles between them, the contact areas would be so
few and so small that little binding could result.
418 Irrigation and Drainage
THE DEMANDS FOR AIR IN THE SOIL
It must ever be kept in mind that an abundance of
free oxygen in the soil is as indispensable to the life
of the plant as it is to that of an animal. The
germinating seeds must have it, or they rot in the
soil ; the roots of plants must have it to enable
them to do their work ; and the vast army of
soil bacteria, which change the nitrogen of decaying
organic matter into nitric acid, which is the chief
nitrogen supply for most higher plants, must have
it or they cannot thrive. Again, those very impor-
tant germs which live on the roots of clover and
other allied plants, and which are the chief source
of the organic nitrogen of the world, must have an
ample supply of both free oxygen and free nitrogen
in the soil, or they are unable to accomplish their
task.
Again, there lives in all fertile soils a class of
germs which have the power of breaking down
nitrates, or even organic matter, to supply them-
selves with oxygen whenever the conditions are such
that the soil does not contain enough to meet their
needs. But when these germs are forced to do this,
as happens in a water -logged or poorly drained soil,
the nitrogen of the soil nitrates and of organic
matter is liberated in the form of free nitrogen
gas, and hence the soil may thus be depleted of
this most expensive ingredient of plant -food wherever
proper drainage does not exist.
Finally, many purely chemical changes taking
Drainage Ventilates the Soil 419
place in the soil, which are essential to its fer-
tility^ demand both free oxygen and carbon dioxide,
so that here is another need for good drainage, in
order that ah* may enter the ground in abundance.
HOW DRAINAGE VENTILATES THE SOIL
Where standing water would be found in holes
sunk 18 to 24 inches below the surface, capillarity
would hold the pores of a fine soil so nearly full
of water to the top of the ground that there would
be little room left for air to enter ; but when the
ground water is permanently lowered three or four
feet, as is done by underdraining, the roots of plants
penetrate the soil more deeply, and, as they die and
decay, leave passageways leading* to the surface, into
and out of which the air readily moves. Earth-
worms, ants, and other burrowing animals penetrate
the ground more deeply, and open other ventilating
flues of much larger magnitude than those left by
the roots of plants, and so greatly increase soil ven-
tilation as a result of drainage.
Then, again, when the deeper clays dry out, as
they will after underdrainage, shrinkage checks form
in them in great numbers, opening tiny fissures
through which the air moves more freely with every
change of temperature and pressure of the atmos-
phere above. With the deeper and more thorough
penetration of soil -air, carrying with it the car-
bonic acid developed near the surface, there begins,
through the agency of the soil water, a solution of
420 Irrigation and Drainage
the lime which in its turn tends to force the fine
clay particles into larger compound clusters, thus ren-
dering the soil more open, and hence better drained,
better ventilated, and at the same time better and
more thoroughly occupied by the roots of plants.
But all of these changes, which result directly
from lowering the ground-water surface, are only
means which make underdrainage more effective in
ventilating the soil. In an underdrained field, where
lines of tile are laid 3 to 4 feet deep and 50 to 100
feet apart, there is provided a very effective system
of soil ventilation as well as of drainage ; for with
every fall of the barometer and rise of soil tempera-
ture, some of the deeper soil -air expands and drains
away through the lines of tile. Then, when the
barometer rises again, or when the soil temperature
falls, a volume of air equal to that which left the
soil under the other conditions now enters it again,
not only through the surface of the ground, but
also through the tile drains. It is thus seen that
a deep, well -laid system of tile drains permits the
free oxygen of the air to reach the roots of plants
both from above and below. Under these condi-
tions, the roots of crops are better supplied with
oxygen ; nitrates develop faster and deeper in the
soil ; there is less occasion for denitrification to set
in, and so larger yields result.
When deep underdrainage has permitted the roots
of plants to penetrate the soil from 3 to 4 feet and
there withdraw moisture, this action on their part
becomes a means for drawing air into the ground,
Drainage Ventilates the Soil 421
both from the surface and through the tile drains,
because the removal of the soil water by the roots
leaves an open space, which must be filled with air
so far as capillarity fails to do it with water, and
hence deep root feeding means deep soil ventilation.
Then, again, when heavy rains fall which move
downward through the soil, they displace both the
air and the water previously there, crowding them
forward into the drains, and then draw in after them
a fresh supply- from above. But only on well-
di'ained soils is this action marked and helpful.
A word should be said here regarding the value
of clover and alfalfa as soil ventilators, for by their
thicker, stronger roots they set the soil aside more than
most other cultivated crops do, and when these roots
decay the soil is left better aerated and better
drained. Further than this, the roots of these legu-
minous plants remove from the soil both free oxygen
and free nitrogen, and in so far as they do this with-
out returning an equal volume of another gas, their
action tends to develop a vacuum which must be
filled by bringing in a fresh supply from without.
TOO THOROUGH AERATION OF THE SOIL
There may be too strong and rapid changes of
soil-air, just as there may be too rapid and complete
drainage. If the air enters a rich, damp soil too
rapidly, there is so strong a development of nitrates
that the humus and other organic nitrogen are quickly
changed into the soluble forms, and rapidly leach
422 Irrigation and Drainage
away. It is in this manner that coarse, sandy soils
are impoverished, and their lack of productiveness
is often due quite as much to too thorough ventilation
as to too complete drainage ; and in handling these
soils the utmost care should be exercised to keep
the content of humus high, the moisture plenty, and
the winds from drifting awaj^ the finest dust particles,
because all of these tend to close up the pores, giving
the soil a texture which diminishes the amount of
ventilation.
DRAINAGE INCREASES THE AVAILABLE SUPPLY OF
SOIL MOISTURE FOR CROPS
When soils are poorly drained during spring and
early summer, the root system of the various crops
is forced to develop near the surface, and if this is
the case until the demands for moisture become large,
the soil in which the roots are confined becomes very
drj^ because capillarity brings the water up from
below too slowly to meet the demand.
It is a familiar fact that a damp cloth is much
better to remove water from the floor than a di'y one,
and the same is true of soils ; water rises by capil-
larity in them when quite moist much faster than
when they become dry, and so it is a matter of the
greatest moment to keep the surface soil, beneath the
mulch, as damp as the best conditions for growth
will permit. When the deeper soil in the spring and
early summer is well drained, and the roots of the
crop penetrate it, they not only find themselves closer
Drainage Increases Available Moisture 423
to the ground water supply, but not so many roots
are forced to take the moisture near the surface, and
hence for this reason capillarity is better able to hold
the water content up to the saturation needed.
With the soil near the surface moist, where nitrates
are mostly formed, a better supply of these is kept
up, while at the same time there is moisture enough
to hold them in solution and to enable the roots
to obtain them. When other roots are deeper in the
ground, these may chiefly draw water to meet the
necessary evaporation which goes on in the leaves,
and thus reserve the surface moisture for developing
plant -food and giving it to the plant. In this way
it happens that crops suffer less in times of drought
on well -drained, heavy soils than they do on the same
soils not drained.
SOIL MADE WARMER BY DRAINAGE
There is no cause so effective in maintaining a low
temperature of the soil in the spring as the water
which it contains, and which may be evaporating from
its surface. One reason for this influence is found
in the fact that more heat is required to change the
temperature of a pound of water one degree than the
same weight of almost au}^ other substance. Thus,
while 100 units of heat must be used to warm 100
pounds of water from 32° F. to 33° F., only 19.09
units are required to raise the temperature of the
same weight of dry sand, and 22.43 units an equal
weight of pure clay through the same range of
424 Irrigation and Drainage
temperature. Stated in another way, the amount of
sunshine which will warm a given weight of water
10° F. will raise the temperature of an equal weight
of dry sand 52.38° F., clay 44.58° and humus 22.6°.
It is plain, therefore, that very wet soils must warm
in the sun more slowly because the water which they
contain tends to hold the temperature down.
The chief cause, however, which makes a wet,
undrained soil colder than the better drained one, is
the cooling effect which results from the more rapid
evaporation of water from the wetter soil surface.
When the bulb of one of two similar thermometers
is covered with a jacket of muslin moistened with
pure water, and the two are swung side by side in
a dry air, it will often be observed that the bulb bear-
ing the moist cloth will have its temperature lowered
as much as 20° F. by the cooling effect of evaporating
water. So, too, when water evaporates from any sur-
face, no matter what, its temperature is lowered in
proportion to the rate at which evaporation is taking
place. The teakettle boiling over the hot fire has
its temperature constantly held down to 212° by the
rapid evaporation of water, although the heat of the
fire playing upon it is very many degrees hotter.
It is the same way with a wet soil through which
water is continually brought to the surface as rapidly
as it can be evaporated in the heat of the sunshine.
The loss of the water in this way necessarily holds
the temperature down, and the lower the more rapidly
the evaporation takes place. The following table*
*The Soil, p. 227.
soil
soil
ence
66.5°
54.00°
12.50°
70.0°
58.00°
12.00°
50.0°
44.00°
6.00°
55.0°
50.75°
4.25°
47.0°
44.50°
2.50°
Importance of Soil Warmth 425
shows the observed difference in temperature of a
drained and an undrained soil :
Temperature
Condition of Temp, of of drained of undrained Differ-
Date Time weather air
At,v;io.i 3.30 to Cloudy, with brisk ^n r;o r,
Apru -4 4 p jjj gj^g^ ^^^ OU.D i) .
Anril ''5 ^ *^° Cloudy, with brisk „ , „o p
Anril "a ^■^'^ ^'^ Cloudy, rain all the 4- qo -p
^ 2 p.m. forenoon
A,„^io7 1.30 to Cloudy and sunshine, rg no tti
April .7 2 p. m. wind S. W. brisk ^^-^ -^ •
4^^4i oa 7 to Cloudy and sunshine, ,e ^o t^
Apru -8 g 3Q j^ j^ .^^^ J jj_ yjr_ |jj.jgj^ 45.0 J! .
The difference in the rate of evaporation from
clayey soil and sandy soil, when both are well
drained, will often be enough to leave the clay
soil 7° F. colder in the surface foot and 5° colder
in the second and third feet below the surface.
IMPORTANCE OF SOIL WARMTH
Ebermayer concluded from his observations that
relatively little growth can take place with most cul-
tivated crops until after the soil temperature has
been carried above 45° to 48° F., and the maximum
results are reached only after a temperature of 68°
to 70° has been attained.
Sachs showed that both pumpkin and tobacco
plants wilted, even at night and with an abundance
of moisture in the soil, when its temperature fell
much below 55° F., the osmotic pressure being then
too feeble to maintain a sufficient movement of soil
moisture to keep the plant cells turgid. Phenomena
426
Irrigation and Drainage
similar to this are often observed early in the spring,
when leaves are jnst unfolding. A strong drying
wind on a cool day, with the soil also cold, withers
the leaves much as if they had been frosted.
The germination of seed is very much influenced
by the temperature of the soil, maize requiring 16
days to appear above the ground when the soil tem-
perature is 60° F., or below, when if the warmth is
72° or above, 3 days or less will do the same work,
besides giving much stronger plants. These effects
Fit,'. i:il. Iiilluenee of soil temperature on the rate of germiuatiou of mai-^e.
of soil temperature are clearly demonstrated in Fig.
131. Indeed, it will often happen that when seed
of rather low vitality is planted in a soil a little too
cold, germination will not take place at all, or if it
Importance of Soil Warmth 427
does, the plants are so much enfeebled that only a
slow growth results afterward.
In the early part of the season, when ground is
being fitted for seeding, it should ever be kept in
mind that one of the chief objects of the early and
thorough tillage is to develop an abundance of
nitrates in the soil for the use of the crop. But
this is done by making the soil warmer, and by
introducing an abundance of air into it when there
is a good supply of moisture associated with the
humus upon which the niter germs feed. These
germs cease to develop niter from humus when the
soil temperature drops to 41° F. ; the action is only
barely appreciable at 54° F., and it reaches its maxi-
mum rate only at a temperature of 98° F.
Now, the early, deep stirring of the soil in the
spring prevents the moisture from coming up from
below, and so lessens the rate of evaporation ; this
allows the soil to become warmer. Besides the heat is
not conducted as rapidly downward when the soil is
loose ; this makes the stirred, well ventilated portion
warmer also, so that for the germination of the seed
and for the development of plant -food, deep early
tillage is very important. It is plain, also, that the
well -drained field not only can be tilled earlier and
deeper, but will also have the soil warmer and richer,
for the reasons just stated.
For the same reason that sugar dissolves faster in
warm than in cold water, so the ash ingredients of
plant-food are dissolved faster, and stronger solutions
of them are formed in the warm than in the cold
428 Irrigation and Drainage
soils, and hence land drainage may be beneficial to
crop growth in this manner.
CONDITIONS UNDER WHICH LAND DRAINAGE
BECOMES DESIRABLE
It must be kept ever in mind that all lands, of
whatever kind, require draining, but it is extremely
fortunate that for most lands this is done by the
natural methods of percolation and underflow of
ground water.
The cases in which it becomes desirable to supple-
ment the methods of natural drainage fall into five
classes : first, those comparatively flat lands or basins
upon which the surface waters from surrounding
higher land frequently collect ; second, areas border-
ing higher lands, whose structure is such as to permit
the underflow of the ground water from the adjacent
regions to rise from beneath, thus keeping the soil
too wet ; third, lands regularly inundated by the rise
of the tides, or which would be if not shut off by.
dykes ; fourth, those extremely flat lands which are
underlaid by considerable thicknesses of close, heavy
beds of clay, through which water does not readily
percolate, and which lie very close to the surface, so
that the clays become the subsoil of the fields, and
fifth, lands like rice -fields, water-meadows and cran-
berry marshes, to which water is applied by irrigation
in excessive quantities. It may also be found desir-
able on some irrigated lands to introduce drainage to
remove injurious salts, as described under alkalies.
Origin of Ground Water 429
THE ORIGIN OF GROUND WATER AND ITS
RELATION TO THE SURFACE
To understand the laws governing the flow of
water into tile drains and ditches, it is necessary to
know how the flow into streams and lakes takes
place, and how the surface of the water in the
ground is related to that in the streams and lakes
into which it is continually draining.
The rains which fall upon the surface tend, first
of all, to sink vertically downward until they reach
the level at which the pores in the soil or rock are
completely filled with water. There are no soils and
very few rocks through which there can be abso-
lutel}^ no flow, but the downward percolation is very
much slower in some than it is in others. This
being true, everywhere beneath the land surface a
place may be reached where the pores are filled with
water, and the level at which this occurs is called
the ground -water surface.
This ground -water surface is seldom horizontal,
but usually rises and falls much as does that of the
ground above it, but with gradients less steep. In
Fig. 132 is represented a section of land adjoining a
lake, where the differences in level of the surface are
shown by means of contour lines passing through all
places, having the height above the lake indicated by
the number set in the line ; while in Fig. 133 the
surface of the ground water for the same area is
also indicated in like manner. The data for the levels
of the ground water were procured by sinking wells
Fig. 132. Contours of the surface of the ground in the viciiiity of a
tile-drained area.
Fig. 133. Contours of the level of the ground-water surface under the
locality represented in Fig. 132.
432
Irrigation and Drainage
at the places designated by the small numbered cir-
cles.
Referring to the two figures, it will be observed
that there is a marked tendency for the ground-
water surface to stand highest where the level of the
field is also highest, and that there are valleys in the
ground -water surface beneath the valleys in the field.
It will be seen that the water rises as the distance
from the lake increases, and that in places it stands
10 and even 20 feet higher.
This distorted surface of the ground water cannot
be a condition of rest, for gravity tends continually to
force a flow from the higher toward the lower levels
along the lines indicated by the arrows shown in Fig.
133. Since the further this water must travel through
the soil to reach the lake the more resistance it must
meet, it is plain that a greater pressure will be re-
rig. 134. Diagram of lines of flow of water in the drainage of a river vaUey.
quired to overcome this resistance, and hence the
water must stand higher in the ground the farther the
distance to the drainage outlet. The space enclosed
by the rectangle in Fig. 133 is an area which required
underdraining to fit it for farm crops, and the reason
it did is clearly shown by the contours of the two
Movements of Ground Water 433
maps and by the arrows representing the lines of
underflow, which concentrate from the surrounding
higher lands to pass beneath this section so near
the surface that the strength of capillarity was suffi.-
cient to over -saturate the soil above. The influence
of the tile drains in lowering the surface of the
ground water is plainly shown by the distance the
contours are carried back from the lake shore, as seen
along the line marked "tile drain."
In the case of streams winding through valleys,
the water comes to them at every point along their
course by slow seepage, entering the channel through
the banks aud bottom in the manner represented in
the diagram, Fig. 134, where the heavily shaded por-
tion represents the soil filled with water and the lines
with arrow points the direction of flow.
In Fig. 135 is represented the surface of the
ground water in the valley of the Los Angeles river,
California. The data for the contours were procured
by sinking wells at the points designated by the
heavy dots. From the map it is clear that the water
stands higher and higher above the bed of the stream
as the distance back increases, and that there must
be a steady flow down the valley and toward the
river, thus draining the surrounding country. Indeed,
in a distance of about 11 miles the measured growth
of the Los Angeles river in 1898 was 60 cubic feet of
water per second, and yet no visible streams entered,
the supply coming by slow seepage along the banks
and bottom of the entire length of the section
measured.
Ground Water Gradient 435
It will be clear, therefore, from the cases cited,
that wherever the moviug sheet of ground water ap-
proaches within capillar}' range of the surface of the
ground, there the soil is liable to be too wet for crops
unless underdrained.
RATE AT WHICH THE GROUND -WATER SURFACE
RISES AWAY PROM THE DRAINAGE OUTLET
In well 29 of Fig. 133, situated 150 feet from the
lake, the water stood 7.214 feet above the level of the
lake June 27, 1892, thus showing a rise of 1 foot in
every 24.4 feet. At another place in the same locality,
but not shown in the map, a well 1,250 feet from the
lake shows the ground -water surface to stand 52 feet
above, thus giving a gradient of 1 foot in 24 feet.
Later in the season, when the ground had become
dryer, the gradient at well 29 became 1 foot in
35.86 feet.
Between tile drains 33 feet apart and 4 feet deep,
laid within the rectangle of Fig. 133, measurement
showed the surface of the water to rise at the mean
rate of 1 foot in 25 feet 48 hours after a rainfall of
.87 inches, and the shape of the ground-water surface
at the time in question is represented in Fig. 137.
Of course, after the lapse of a longer interval of
time the gradient here would have become less steep,
just as was the case in the other instance cited.
The subsoil in which these gradients were observed
was a fine sand, in some places with grains so small
as to approach the character of quicksand, and they
436 Irrigation and Drainage
represent conditions which are very common in locali-
ties where underdi-ainage is needed, and, therefore,
furnish a good basis upon which to form a judgment
regarding the distance apart tile should be laid.
DEPTH AT "WHICH DRAIN'S SHOULD BE LAID
The depth to which water should be lowered by
di-ainage need seldom exceed 4 feet for ordinary farm
crops, and often the lowering of the water surface
may be less.
It should be kept in mind that the level of the
ground water changes with the season, and that many
lands benefited by underdi'aiuage are only too wet
earh- in the spring, and if such lands are to be used
for ordinary farm crops, it may onh' be needful to
draw the water down so far as to make the surface
dry enough to give good working conditions for the
soil. In such cases, tiles placed 2% to 3 feet deep,
rather than 3% to 4 feet, will usually be found suffi-
cient. If the tiles are placed deeper than this, not
only AviU there be a permanent lowering of the ground
water, but the low stage wiU be reached so much
earlier in the season that a smaller amount of the
water flowing under the field may be used by the
crop.
Where fields are underlaid by sandy subsoils, it
is quite important not to di'aw the water down far
into the sand, because the height to which the water
can be lifted rapidly in these by capillarity is quite
short. To carrv the ground -water surface below this
Distance Between Drains 437
limit not only lessens the amount of underflow which
becomes available to the crop, but it also diminishes
the amount of the heavy summer rains which the
crop may use, because when the ground water is
carried too low much of the water, in times of pro-
longed heavy rains, may pass below the limit of root
feeding before the crop has time to avail itself of it,
DISTANCE BETWEEN DRAINS
There are three chief factors which determine the
proper distance between underdrains : (1) the freedom
with which water may flow through the subsoil
toward the drains, (2) the depth at which the drains
are placed, and (3) the interval of time between
rainfalls sufficiently heavy to produce considerable
percolation .
It should be clearly understood that it is the
character of the subsoil, rather than that of the
soil, which determines the rate at which water moves
toward and into the drains, and it should be further
understood that the subsoil which takes part in the
lateral flow of the water may be several feet, even 10
or more, below the level at which the drains are
laid.
If, for example, the field to be drained has a
rather close clay surface soil underlaid with two, three
or four feet of heavy clay, which in turn is underlaid
by a stratum of sand, then the movement of water
from the surface toward and into the drains will
be such as is represented by the arrows in Fig.
438
Irrigation and Drainage
136. That is, the water moves along the line of least
resistance, no matter how circuitous or how long that
may be.
Where the cavities through which the water must
flow are those due to the diameter of the soil grains,
/;
*v'ri^'P^^€>-'
: T ''•?-:.>
' :i ' ' ' "."'
' " •■ ■ ' "
wr-!P
^
1,' j'
1
-^TT
'\y\\-:Z.
-, Z'
— . ^
\ -
-^^^
■/I^'^
Fig. 136. Movements of water toward tile drains where heavy clay
soils are underlaid with sand.
the influence of size of grain on the rate of flow
is such that the amount of water passing a given
section under otherwise like conditions is somewhat
nearly proportional to the squares of the diameters.
This being true, if the effective diameter of the
grains in the clay is .004 m.m., while that of the
grains in the stratum of underljiug sands is .07
m.m., then their squares will be .0049 and .000016
respectively, in which the ratio is nearly as 300 to
1, so that the water would flow through the same
length and section of sand about 300 times as rapidly
as it would through the clay.
It is also true that the lengths of the soil pores
through which water flows decrease the rate in a ratio
nearly proportional to the lengths, so that the sand
column in the case cited, or, what is the same thing,
the distance between drains, could be 300 times as
great as with the clay and yet leave the rate of flow
just as rapid. It is plain, therefore, that the move-
Distance Between Drains
439
ment of the water in cases like that represented in
Fig. 136 will be chiefly straight down through the
soil and clay until the sand is reached, when the
movement will be sideways toward the drains and
finally upward, the water entering them chiefly from
the under side. That is to say, the flow sidewise
through the claj' toward the drains will be very slight
indeed.
Since the resistance to flow of water increases as
the soil texture becomes more close, it is clear that
the more open the soil the farther apart the drains
may be placed. It is common to place lines of tile
in underdraining varying distances apart, from 30 feet
to 100 and even 200 feet. The reasons for these wide
differences will be better understood after considering
the way the ground -water surface changes under a
tile -drained field following a rain.
Fig. 137. The observed surface of the grouud water in a tile-drained field
48 hours after a rainfall of .87 inches.
In Fig. 137 is represented the observed slope of the
ground -water surface in a tile -drained field where
the lines are placed 33 feet apart and between 3 and
440
Irrigation and Drainage
4 feet below the surface. The conditions there shown
had developed 48 hours after a rainfall of .87 inches,
and the facts were obtained by sinking lines of wells
at right angles to the drains, there being 3 wells
between each pair. It will be seen that the height of
the water on the crest between the drains varies,
being much greater at 1 and 2 than elsewhere, and
this is where the soil is more clayey, and so closer in
texture.
In Fig. 138 is represented the heights of the
ground -water surface midway between the drains as
they occurred 2 days, 2% days and 5% days after the
same rain, and the differences in the steepness of the
slopes in the several cases should be understood as due
chiefly to differences in the size of the soil grains. It
will be seen that after a period of nearly 6 days the
surface of the ground water in the upper portion of
Fig. 138. Changes in the level of the ground- water surface in tile-drained field.
the field has become quite flat, having fallen below the
level of the di*ains, and the gradient being reduced
to 1 foot in - 175 feet, while at the lower end, where
the soil is heavier, the slope is still 1 in 27.
Taking these two cases, let it be assumed that it
Distance Between Drains
441
is desired to place the liues of tile close enough
together, so that after 6 dajs following an inch of
rain the water shall nowhere stand within 3 feet of
the surface, and that the tiles are placed 4 feet deep.
Since in the sandy subsoil of the upper part of the
Fig. 139. Diagram of influence of distance between drains on
depth of drainage.
field the mean gradient is 1 foot in 175, the lines
of tile may, under such conditions, be placed twice
this distance apart, or 350 feet, for then halfway
between them the water would only stand 1 foot above
the drains and hence 3 feet below the surface. But
in the lower part of the field, where the soil is finer
and where the observed mean gradient is 1 in 27,
the lines of tile could only be placed 54 feet apart
to ensure the same conditions.
It was pointed out, in connection with Fig. 133,
that the slope of the ground water toward the lake
was at the rate of 1 foot in 24.4 early in the season,
and later 1 foot in 35.86 feet, which would call for
placing the lines of tile 50 to 72 feet apart. Refer-
ring to the diagram, Fig. 139, it will be readily under-
stood that when there is a drain at A and C only,
the soil undrained must be highest at B, but if an
442 Irrigation and Drainage
intermediate line of tiles is placed at D, then the
highest levels of the ground water would be found at
E and F, farther below the surface, leaving the field
better drained. It is very important that this prin-
ciple be thoroughly grasped, because so many local
conditions affect the depth and distance apart at
which drains should be placed that no specific figures
can be safely followed in all cases. It is generally
true that in loose, loamy soils, and especially if under-
laid by sand, good drainage will be secured with
drains 100 feet apart and 3% feet deep. On heavier
soils, they must be closer, and on more open ones
they may be farther apart.
In regard to depths of drains, it should be under-
stood that the deeper they are placed the better work
they do as a rule. If one soil has had its non-
capillarj^ pores -emptied to a depth of 4 feet, and
another one only to a depth of 2 feet, the capacity
of the former to store a heavy rain without over-
saturation will evidently be greater than that of the
latter, and hence the shallow drained fields will oftenest
become over -wet in wet seasons. But the cost of
digging 4 feet is much greater than 2% feet, the
expense increasing faster than in proportion to the
depth.
In cold climates the tiles must be placed as deep as
2 feet, to prevent their destruction by frost. Tiles
are laid at a depth of 18 inches, but the practice is
not only unsafe so far as destruction of the tiles is
concerned, but not half the advantage can then be
secured which they are capable of giving if laid deeper.
Kinds of Drains 443
KINDS OF DRAINS
Drains are called closed or open, according as they
are covered or not. There are conditions under which
open drains or ditches should and must be used, but
the closed forms are always to be preferred where
thorough drainage and facility in working the land
are desired. In the earlier practice of underdraining,
before tiles were invented and manufactured on a
large scale, various means were adopted to provide
waterways through which the water could more readily
drain away from the field. An early method was to
place in the bottom of a ditch bundles of faggots end
to end and then fill in, expecting the water to flow
through the spaces between the faggots. Three
slender poles were often used, one laid upon two
others, thus forming a waterway ; or again, a single
larger * pole was split in two and these laid in the
ditch side by side with the flat faces up. Two boards
nailed together V-shaped and laid on the bottom of
the ditch formed still another method of securing
underground drains with wood.
Stones were also used in various ways for the same
purpose ; sometimes the bottom of the ditch was
filled with small stones and then covered ; two rows
of flat stones placed .on edge to form a V opening
downward, was another common plan. Two flat
stones on edge, with a cover, were extensively used,
and some even went to the trouble of paving the
bottom of the ditch with flat stones and forming a
closed stone drain by adding sides and top, which,
444 Irrigation and Drainage
when well done, was permanent and effective. Square
blocks of peat have been grooved on one face and
two of these placed together to form a tile, thus
making a drain of another kind. Each of these
methods of securing underdrainage involved much
labor ; gave channels in which the water flowed with
great resistance ; clogged easily, and while beneficial
results invariably followed their use, they v/ere neither
wholly satisfactorj^ nor permanent.
When the manufacture of tiles from burned clay
was begun, various shapes were adopted and abandoned
for the present cylindrical type, which when well
made and laid, has been found entirely satisfactory
for the construction of closed drains.
In more recent years an effort has been made to
build a continuous line of tiles in the bottom of the
ditch after it is dug and graded, using a concrete
made from the best hydraulic cement, lime and" sand.
The mortar, when made, is fed through a simple
machine, which determines the size and shape of the
tile, making it continuous, cylindrical and smooth on
the inside. A trowel is used to cut the tile through
to near the lower side with sufficient frequency to
permit the necessary percolation from the soil, thus
securing a drain with all joints perfect. The system,
however, has not been sufficiently long in use to
enable one to say how meritorious it is.
Open surface drains, where they are permanent
improvements, should, if possible, be made wide and
with sides so gently sloping as not to be washed, and,
if possible, so as to be grassed over and driveti through
Kinds of Drains 445
with mowing machine, both to keep it clean and to
utilize the land for hay. In many flat prairie sec-
tions there are "runs," "draws," "sloughs" or natural
waterways, through which the surface waters find
their waj', in the spring and at times of heavj- rains,
into drainage channels. Such drainage must usually
be handled in surface drains, and even when the
channel must iu places have a depth of three feet,
it will be cheaper and far better in the long run to
make them with sloping sides not steeper than 1 in
2, or 12 feet wide at the top. If the work is done
in the diy season, most of it can be accomplished
with plow and scraper, and the earth moved back,
smoothed down and seeded to grass so as to make
it permanent, easily cared for, and not a serious
obstruction.
Where turns must be made in such drains, they
should have a large curvature to prevent the water
cutting into the bank.
HOW WATER ENTERS TILE DRAINS
The flow of water into the tile di-ains takes place
through the walls of the tiles and through the joints
made by abutfiug the ends together. It is a common
impression that considerable space should be left
between the ends of the separate tiles, in order that
the water shall have opportunity to enter, and that it
is quite necessary that the lengths of the tile shall be
short, in order that there shall be sufficient space
left for the passage of the water.
446 Irrigation and Brainage
The facts are, however, that there is so ready a
movement through the walls of ordinary tiles them-
selves, and through the joints when they are made as
perfect as possible, that every precaution should be
taken in laying tiles to make perfect joints, in order
that the silt and soil may be excluded, to prevent
clogging the drain.
A series of observations on 2 -inch Jefferson, Wis.,
tiles, relating to the rate of percolation through the
pores in the walls, showed that under a pressure of
23.5 inches the discharge per 100 feet into the tile was
at the rate of 8.1 cubic feet during 24 hours. This
occurred when the walls were surrounded by water
only. When the tiles were covered with a fine clay
loam, so that water had to flow through 3 inches of
this soil to reach the tiles, the discharge was reduced
to the rate of 1.62 cubic feet per 100 feet of tile in
24 hours. It is plain, therefore, that with this poros-
ity and with the openings at the joints, there is
ample opportunity for the water to find its waj' into
the drains after reaching them, and great pains
should always be taken to make as close joints as
possible.
The use of collars to keep sediment from entering
the joints is not a good practice. They will not, as
a rule, fit closely ; they tend to encourage careless
laying ; they increase the first cost, and the soil, if
it works under the collars so as to fill the space, will
retard the entrance of water into the drain. Tile well
made, with ends square and whole, if properly laid,
make a sufficientlj' close joint.
Gradient of Drains 447
THE FALL OR GRADIENT FOR DRAINS
In most cases where drainage is required, the sur-
face of the field is so flat that it is usually desirable
to secure as much fall for the drains as it is prac-
ticable to get, and so a careful study of the field
should be made with a view to learning where the
lowest land is and along what line the greatest rate
of fall may be secured. This is a matter of the
greatest importance, and the less the fall is the
greater should be the attention given to it. If a fall
of 2 inches or more in 100 feet can be secured, the
conditions are favorable for good results. It often
happens that less fall than this must be accepted, but
this should be done only after careful leveling has
proved a greater one impracticable.
It will frequently happen that the line of lowest
ground is quite tortuous, making the distance from the
highest to the lowest point greater than to follow a
straight line. When this is the case, and the fall
very small, it may often be desirable to dig a little
deeper in places, cutting off bends, and thus increase
the fall.
It will generally be true, however, that the main
drain should follow the lowest line in order to secure
as much fall for the laterals as possible, and this
point is made the more important because the axis
of each lateral should reach the main above its center,
in order that water in the main shall not set back
into it.
Great pains should always be taken to get a per-
448
Irrigation and Drainage
fectly uniform fall for the whole main or the whole
of any given lateral, and the greatest care should be
exercised to lay the tiles ijerfectly true to the grade
when that has been determined. When this is done,
there is the least tendency for sediment to lodge and
clog the drain.
It will not be possible in all cases to maintain a
constant gradient, and when this is true it is best
always to change from a less fall to one which is
greater, because then any sediment which should be
carried in the upper part
of the drain will also be
carried when the fall is
increased ; but with the
reverse conditions the
lower fall must have a
tendency to cause the
drain to become clogged.
Where a change from
a larger fall to one less
must be made, and the
latter gradient is 3 inches
per 100 feet or less, it
will usually be prudent
to place a silt basin where
the change of grade oc-
curs, as represented in
Fig. 140. The silt basin, if the line of tiles is short
and small, may be made by sinking an 8-, 10- or 12-
inch tile below the level of the bottom of the ditch,
and then notching another section of the same size,
Fig. 140. Silt basin.
Size of Tile 449
so that it may receive the drain from above and be-
low. The sediment brought will then be dropped in
the still water of the basin, and may be removed from
time to time. To bring the silt basin to the top of
the ground, it will be best to use one length of the
glazed sewer tile, because this will not be injured by
freezing. Where the line of tiles is large, and much
sediment is likely to be moved, the silt basin should
be dug larger and bricked up. Silt basins should be
kept covered to avoid accidents, and especially in win-
ter, to prevent injury to the tile by freezing.
SIZE OF TILE TO USE
It is not possible to give specific directions for
selecting the sizes of tiles which are best, except where
all the details regarding the field to be drained are
known. It may be said, in general, that their capacity
must be large enough to remove the excess of water
of the heaviest rains which fall inside of 24 to 48
hours, but how much this excess may be will vary
between wide limits.
If the tile are 3% to 4 feet deep, and the soil has
been depleted of its moisture by a heavy crop, the
cases are very exceptional when even a rainfall
of 2.5 inches in 24 hours would produce much per-
colation into the drains. It is the rains in the
spring of the year which will most tax the drains,
but it should be understood that so long as the
water is moving quite rapidly through the soil it is
sucking fresh air in after it, and there is little danger
00
450 Irrigation and Drainage
to crops, and for this reason mueli smaller tiles are
permissible than would otherwise be the case. It is
when the ground water in a cultivated field becomes
stagnant or stationary that poisonous principles are
developed and suffocation for lack of air occurs.
The gi-eater the gradient or fall of the line of
tiles, the greater will be its capacity and the smaller
it may be for a given area. The area of cross-
section of tiles increases in the ratio of the squares
of the diameters ; thus for diameters of tiles of 2,
3, 4, 5, 6, 7, 8 and 9 inches, the areas will be 4, 9,
16, 25, 36, 49, 64, and 81 square inches, and hence,
when running full with the same velocity, their
capacities would be in the relations of the second
series of numbers. The friction on the walls of the
tiles, and the eddies which the joints and other ine-
qualities tend to set up, reduce the velocity in the
small tHes more than they do in the large ones,
hence doubling the diameter of tiles considerably
more than makes its capacity four times as great.
The longer the line of tUes the less it is able to
discharge when running fuU, but just how much the
capacity is decreased by the length cannot be simply
or accurately stated.
In speaking of the proper size of mains, C. G.
Elliott* states : " For drains not more than 500 feet
long, a 2 -inch tile will drain two acres. Lines more
than 500 feet long should not be laid of 2 -inch
tOes. A 3 -inch tile will di-ain five acres, and should
not be of greater length than 1,000 feet. A 4 -inch
♦Practical Farm Drainage, p. 57.
Size of Tile 451
tile will drain 12 acres ; a 5 -inch, 20; a 6 -inch, 40 ;
and a 7 -inch tile 60 acres."
In the earlier practice of underdraining with cylin-
drical tiles, sizes as small as 1% inches were used for
the laterals, leading the water into the mains, but the
general tendency has been to abandon the smaller
sizes and to use nothing less than 3 inches in
diameter, even for the laterals. The labor of making
the small sizes is nearly as great as that required for
those 3 inches in diameter, thus leaving the differ-
ence in cost chieflj^ that of the extra amount of stock
used in the manufacture. But the 3 -inch size is so
much safer to use than the smaller ones that the
latter should generally be abandoned. The most seri-
ous objection to the small sizes is the great difficulty
in laying them so exactly to grade as not to have
them silt up.
The sizes of mains and sub -mains, the sizes of
laterals, the lengths of each size used, and the dis-
tance between drains, can best be shown by citing a
specific case where the conditions to be met have
been considered in making the selections and adjust-
ments. The case selected was laid out under the
supervision of C. G. Elliott, C. E., and is an 80-acre
farm in northern Illinois, where the soil is a deep,
rich, black loam, approaching muck in its lowest
places, and underlaid at a depth of 2.5 feet with a
yellow clay subsoil. The fall of the main drains in
this case is not less than 2 inches per 100 feet, and
that of the laterals is more rather than less.
The diagram. Fig. 141, shows that the least distance
452
Irrigation and Drainage
between laterals is about 150 feet ; an effort was not
made to secure perfect drainage, but rather so nearly
sufficient for ordinary crops as to make the increase
in yield pay a fair return for the money invested.
Fig. 141. Drainage system of 80 acres. Double lines represent mains ; single
lines are laterals. Numbers give length of drains and diameter of tile.
After C. G. EUiott.
The double lines represent the mains and sub -mains;
the single lines are laterals, and the numbers of three
or more figures express the number of feet of each
size used in the line against which the.y stand, while
the single figures under these show the inside diame-
ter of the tiles used.
It will be seen that the main begins with 1,000
feet of 7 -inch tiles, carrying the water from 80 acres
of flat land surrounded by comparatively level fields ;
next follow 1,200 feet of 6 -inch tiles, then 600 feet
of 5 -inch, the line closing with 157 feet of 4 -inch
tiles into which no laterals lead.
Outlet of Drains
453
THE OUTLET OF DRAINS
Great pains should be taken to secure a clear fall
at the outlet of a <irain, placing it, if possible, where
it will always be above water, as represented at A,
Fig. 142, rather than as at B. If the outlet is beneath
water, the checking of the velocity of outflow will
cause sediment to be thi-own down, and will soon clog
the main. Care should also be taken to so guard the
outlet from the trampling of animals that they shall
Fig. 142. Proper and improper outlet of drains. A, proper outlet ; B, improper
outlet ; C, proper junction of lateral -with main ; D, improper junction.
not break down the earth about it ; and against the
effect of winter frosts and surface rains, tending to
throw earth down over the mouth.
In cold climates it will not do to terminate the
main with the ordinary drain tile, as the action of the
frost will soon crumble it down. A common plan is
to make a wooden outlet, 16 feet long, out of 2 -inch
lumber, thus holding the tile back beneath the sur-
face sufficiently far to be safe against freezing. A
much better termination of the main, however, and
one which will be permanent, is glazed sewer tile,
using not less than 10 feet of it. Lap -weld iron pipes
454 Irrigation and Drainage
are also used for this purpose, but a section or two of
the cast iron sewer pipe of the size of the main will
be found better, because more durable.
Where the laterals are connected with the mains,
an effort should be made to introduce the branch
above the axis of the main, and where there is fall
enough to permit of doing so the method used exten-
sively in Europe
'^^^j^^^j^j^jj^e^^^j^;^^^ seems to be the
, _ , _.,.^ _, best. This con-
, . I , ,^i^ sists in perforating
the top of the main
Fig 143. Method of connect- -i . i i . - n
ing lateral with main drain. ^ud the bottom of
AfterJtii. Kuhn. the end tile of the
lateral, placing the
two openings together, as represented in Fig. 143, but
fii'st closing the ends of the tile with a stone and ball
of clay. This arrangement allows the lateral to empty
itself completely into the main, and prevents it from
becoming clogged with sediment by the setting back
of water into it.
Where connection is made direct with the side of
the main, it should be done by approaching at an
angle down stream, as shown at C, Fig. 142, rather
than as at D. This can be done, even if the lateral
is at right angles to the main, by curving the ditch
gently for a rod or more as the place of junction is
approached. With this mode of joining, the least
interference is brought about when the two currents
unite and there is the least tendency to clog.
Obstructions to Brains
455
OBSTRUCTIONS TO DRAINS
In all cases where water flows through the drain
during any considerable portion of the growing season,
care must be taken to avoid the presence of trees
Fig. 144. Showing roots of Eiu'opeau larcli removed from a 6-iucli tile
drain, which they had effectually clogged.
anywhere within three or four rods of the line of tile,
otherwise the roots will find their way into the drain
through the joints, and there branch out into a com-
456 Irrigation and Drainage
plete mat of fine fibers, which will fill the whole drain
and by arresting the silt moving with the water, com-
pletely closes it. In Fig, 144 are shown two bundles
of roots of the European larch which entered and
completely choked a 6 -inch main lying 5 feet below
the surface, and where the trees were standing 15 feet
away from the line. There are but few trees that
will grow in such places which can be trusted near
the drain, but the willow, elm, larch or tamarack, and
soft maple are among the worst. It should be under-
stood that so long as the water in the drain is flowing
it is highly charged with air, and trees may even bet-
ter immerse their roots in this than in the more
stationary water between the soil grains, hence they
do so wherever opportunity is offered, unless the water
should be poisonous.
LAYING OUT SYSTEMS OF DRAINS
In preparing to drain a piece of ground of con-
siderable extent, careful study should always be given
to the best way of laying out the system so as •' to
secure the greatest fall and the most complete drain-
age with the least digging and the smallest number
of feet of tile at the lowest cost. To do this, care
must be taken to avoid laying the lines so as to
bring their influence within territory already sufi&ciently
drained by another line ; to make the outlets and
junctions as few as possible ; to avoid the necessity
of the more expensive large sizes of tiles, and of dig-
ging more deeply than is required for good drainage.
Systems of Drains
457
In Fig. 145 are represented diagrammatically two
ways of laying out a system of drains for the same
piece of land. The area drained is about 14 acres,
and with lines of tile laid 100 feet apart, system
A requires 625 feet of 4 -inch and 3,020 of 3 -inch
tiles, while that of B makes necessary only 550 feet
A B
Fig. 145. Two systems of laying out drains.
of 4 -inch and 2,830 feet of 3 -inch tiles to drain
equally well the same area.
Where long lines of tile must be laid in which
more than one size will be required, three systems
have been adopted, that represented in A, Fig. 145,
already described ; a second, A, Fig. 146, and a third,
B, in the same figure. In the case of A, Fig. 146,
covering a section 2,000 feet by 900 feet above the
458
Irrigation and Drainage
«' 3' 3"
3' 3' 3*
S
s
S' 8" 3'
y
s<
line a a, there would be required 9,000 feet of 3-inch
tiles and 9,000 feet of 4 -inch tiles, with lines laid
100 feet apart ; but following the second system, B,
it would only be neces-
sary to lay 3,000 feet of
4-inch tiles, with 15,300
feet of 3 -inch. At 1
cent per foot for 3 -inch
and 1.6 cents for 4 -inch
tile, the difference be-
tween the purchase price
of the two sets of tile
would be $33 in favor
of the system B. The
saving grows out of the
fact that one line of 4-
inch tile has ample ca-
pacity to drain not only
Fig. 146. Two systems of lajring out drains. ^]jg strip of grOUud it
traverses, but at the same time to discharge the water
gathered by the three lines of 3 -inch tile emptying
into it from the upper half of the field.
It will be observed that in both diagrams the nine
lines of tile have been brought to one outlet in the
stream, rather than to make them all separate, as
might be done in A, or to make three outlets, as could
readily have been done in the case of B. To have
finished the system with three outlets would not have
been a bad or expensive plan, but to have as many
outlets as there are lines of tile is not generally to
be recommended.
Intercepting Underflow
459
In actual practice, it will usually be found that no
single system, such as has been represented, can be
used alone, but rather a combination of them in
various ways growing out of the irregularity of slopes
and surface conditions.
INTERCEPTING THE UNDERFLOW FROM HILLSIDES
Cases are not infrequent where seepage from the
high lands surrounding a flat area approaches so close
to the surface at the foot of the rising ground that a
single Hue of underdrains placed here at a good
Fig. 147. Structural conditions producing swamp lands by underflow, and
methods of intercepting the underflow.
depth will so completely intercept the underflow as to
make little other draining needed. The structural
conditions which render underdrainage in such cases
needful, the method of accomplishing it, and the
underlying principle, are represented in Fig. 147.
In this case the comparatively impervious rock
bottom of the valley holds up the water and forces
460 Irrigcdion and Drainage
it to spread laterally and to underflow the low ground
through the sandy stratum covered by the closer
textured layer above, and to rise up through that
soil layer, both by hydrostatic pressure and by cap-
illarity, and thus keep it too wet for agricultural
purposes. But when tiles are placed at A and B,
at the foot of the high lands on both sides, the water
can more easily escape into the drain than it can flow
on through the sand stratum, and the result is, the
pressure which before was forcing the water beyond
A to the left and beyond B to the right may now be
so nearly all absorbed by the flow of water into the
tile drains that no more water reaches the flat land
between them than is needed to meet the demands of
vegetation and surface evaporation. The case is
exactly similar to what is shown in the lower portion
of the diagram ; here it is plain that if water is
allowed to discharge at C and D nearly as fast as the
pipes can bring it from the reservoir, there would
be little left to pass on and escape through openings
beyond, while if C and D are closed, the full pressure
would operate to increase the discharge at lower
openings, as at E.
DRAINING SINKS AND PONDS
It frequently occurs that low places are entirely
surrounded by such high lands as to make it diflicult
to provide an outlet for the surface water which col-
lects in them, especially during the winter and early
spring, keeping them too wet for agricultural purposes.
Draining Sinlcs and Ponds
461
Where the water collecting in such places is
largely from surface drainage, it is frequently possible
to reclaim them by intercepting the water and divert-
ing it around the sink in the manner suggested in
Fig. 148, where A B
represents a surface
ditch taking the water
from the higher land
above.
It is frequently true
that such low places
without natural outlets
are underlaid with well
drained beds of coarse
sand and gravel, and
in such cases, if the
volume of water is not
very large and if the
bed of sand and gravel
beneath it is thick and only 10 to 15 feet from the
surface, a well sunk into the sand and gravel and
stoned or bricked up may serve as an outlet for under
or surface drains.
Instead of curbing the well, it may be simply filled
with loose stones to within 3 feet of the surface,
covering these with smaller ones and finally with
gravel and then sand, leaving the surface unobstructed.
Unless the approach to this drain is so gradual
that there is no danger of fine silt being deposited over
it, it would be better to have this in a shallow sink
surrounded by a slightly higher border, grassed over
Fig. 148. Method of intercepting surface drain-
age. A, B, surface ditch.
462
Irrigation and Drainage
to hold back the water and throw down the sediment
before reaching this place, as shown in Fig. 149,
where a pit has been sunk into the porous gravel
below and broadened at the surface to give more area
for percolation through the finer material at the top.
There are also represented lines of underdrains leading
to the filter outlet, which might be needed in order to
bring the land quickly into the best condition. If
necessary, a line of such wells may be formed in a
surface ditch or depression, and thus increase the
capacity.
THE USE OF TREES IN DRAINAGE
In some instances where sinks without available
outlets are to be drained, and where the method
illustrated in Fig. 149 cannot be used, it is pos-
%^>^
— ■ , ' ■ ' ,1 .|l^il'**ll.(^,(,,,^^^r,J•illlulM
> -^ „ - \^ ;■
Fig. 149. Method of draining sinks.
sible to throw up lands of higher ground with deep,
open ditches between them, in the lowest portion of
the sink, into which the other ground may be drained,
and then plant water -loving trees, like the willow or
larch, on the sides of the ditches, where, by their
Draining Sinks and Ponds
463
rapid growth and large evaporation of moisture
through the foliage, considerable amounts of water
will be removed. The most serious objection to the
method is the fact that the trees will not render their
greatest service early in the season, and may not fit
the ground for early crops other than grass.
THE USE OP THE WINDMILL IN DRAINAGE
In such places as those under consideration in the
last two sections, a good windmill may be made to
drain a considerable area of ground where only the
Fig. 150. Method of draining sinks by wind'power.
underflow must be handled, and where the lift need
not be more than 20 feet.
If the water is to be raised to a level at which
gravity will remove it, then a sump or reservoir
should be sunk in the ground as near the place where
the water is to be disposed of as practicable, deep
enough to hold the drainage of two or three days
when, for lack of wind, the mill may be idle.
In order that the mill may work during the winter
also in cold climates, the pump may be placed in a
464 Irrigation and Drainage
well, as in Fig. 150, into which the main drain, A,
discharges, and from which there is an overflow, B,
to the reservoir. The object of the well is to place
the pump under conditions where it will not freeze in
the severest weather, and thus prevent the ground from
becoming over- saturated at any season. The water may
be made to discharge through an under -ground drain
connected dii-ectly with the pump, as at C, or a flume-
box above ground may be used, as is most convenient.
It might even be practicable to have this drainage
water discharged into a reservoir and used for irriga-
tion at a lower level during the dry season of the
year, or it would be practicable to discharge it into a
series of tiles laid 2 feet below the surface on a
section of higher ground which is naturally well
drained, and thus sub -irrigate this at the same time
the low place is being drained, the two systems caring
for themselves continuously.
LANDS WHICH MUST BE SURFACE DRAINED
There are many ancient lake bottoms now consti-
tuting wide stretches of very flat country underlaid by
heavy deposits of a very close lacustrian clay, through
which water percolates with extreme slowness. Such
lands must generally be surface drained, not only
because it is difficult to find adequate fall for proper
outlets for underdrains, but because the water would
not reach underdrains quicklj^ enough to meet the
demands of crops unless the lines were laid closer
together than could be afforded.
Surface Drainage 465
Even through a clay loam* it may require 24 hours
for 1.6 inches of water to percolate through a stratum
of soil 14 inches deep when the surface is kept under
2 inches of water, and since the rate of percolation is
somewhat nearly proportional to the length of the
column, 2 days would be required for the same flow
through 28 inches, and about 13 days through 15 feet,
the distance the water would have to travel with
underdrains placed only 30 feet apart. But the sub-
soils of the lands in question are much closer than
the loam cited, so that the best which has yet been
done for such soils is to plow them in narrow lands,
with the dead furrows extending along the slope of
the fields in such a way that the excess of water may
be quickly led away into the streams or open ditches.
It is true that the tillage and heavy cropping of
such soils, especially during dry seasons, tend to cause
the clay subsoils to shrink into cuboidal blocks, and
thus facilitate underdrainage ; but the long years
which some of those lands have been under such
treatment without marked amelioration appear to
leave little hope of ever bringing them under thorough
drainage in this way.
There are other flat sections of country, with more
open soils and subsoils, where sufficiently deep open
ditches may be provided to serve as outlets for under-
drains, and lands be thus thoroughly reclaimed. Such is
the case in Illinois, and Fig. 151 represents six square
miles of land treated in this way. In this figure the
double lines represent deep open ditches, the single lines
* The Soil, p. 171.
DD
466
Irrigation and Drainage
underdrains, and the small squares cover 40 acres
each.
Another drainage system of this sort in the same
state is found in Mason and Tazewell counties, where
by a cooperative plan the open ditches have been dug
Fig. 151. Plan of drainage of lands of the Illinois Agricultoral Company,
Ronton], niinois. After J. O. Baker. The smallest squares are 40
acres; double Unes show open ditches ; single lines are tile drains.
and the expense divided among the landowners in
proportion to the benefits derived. The work was
begun in 1883, completed in 1886, and has 17.5 miles
of main ditch 30 to 60 feet wide at the top and 8 to 11
feet deep. Leading into these mains there are five
laterals 30 feet wide at the top and from 7 to 9 feet
deep, the whole system embracing 70 miles of open
ditch, excavated for the express purpose of providing
outlets for underdi-ains after the manner of Fig. 151.
CHAPTER XIII
PRACTICAL DETAILS OF UNDEBDBAINING
To do the best work in underdraining requires not
only a thorough knowledge of the principles, but an
extended practical experience in laying out systems of
drains. The man who has a thorough grasp of this
business, and is experienced in laying out work and
in the use of precise instruments for leveling and
establishing grades, can, with the aid of eye and
instruments, determine rapidly and accurately in the
field the best place for the mains and sub -mains with-
out making a detailed survey ; and where large areas
are to be drained, especially if the fall must be small,
it will usually be safer, better and cheaper to employ
some man of experience who can be trusted to do the
work of leveling, determining grades and accurately
staking out ready for the ditcher both mains and lat-
erals.
Indeed, if a considerable amount of work is to be
done, it will in most cases be better and cheaper in
the end to entrust the whole job to a man who makes
underdraining his business, and who employs and
superintends his own crew of trained men. The mat-
ter of ditching, even, is so much of an art that both
intelligence and experience are required to do it well.
(467)
468 Irrigation and Drainage
So true is this, that a good drainage engineer employs
his men by the season or longer, if possible, and
divides his work among them in such a way that each
man does only one kind of digging. In this way each
one becomes an expert in his place, doing more and
better work with less effort than is possible in any
other way. The man who finishes the bottom of the
ditch and the man who lays the tiles must not only
be skillful, but must be thoroughly trustworthy and
patient, or faulty work will be done. The work
is often so unpleasant, defects are so easily covered
from inspection, and it will be so long before they
could be discovered and the responsibility properly
placed, that only men of peculiar fitness should ever
be trusted with it. These men must be well paid,
they must not be crowded, and there must be nothing
else to take their attention. When the right sort of
man has been secured for this work, and has been
trained to it, he is far more to be trusted than almost
any farmer, even for whom the work is to be done,
because the farmer will have so many other things to
take his attention, and he will be so anxious to have
the job off his hands, that his patience will not per-
mit him to take the necessary time to get every joint
of the 100,000 just right before it is left. Important
drainage work, then, should be left to expert men
wherever practicable.
It is very important that the farmer who has land
to drain should thoroughly appreciate these essential
conditions for safe work, not only to prevent himself
from undertaking what he cannot hope himself to do
Drainage Levels
469
well, but, what is more important, that he may be
able to recognize the essential qualities in the man
who will place the tiles, and satisfy himself that he
possesses them.
It will often happen, however, that drainage
experts cannot be had, and there may be small areas
to drain, involving relatively but small expense,
where the farmer may do his own work or super-
vise it.
METHODS OF DETERMINING LEVELS
Where the services of a man with instruments for
determining levels for lines of drains cannot be had,
there are various simple means for doing this work
which may be employed „ a
where great accuracy is not J[]l ^^^^ Jl
required, and among these
perhaps the safest is the water-level,
represented in Fig. 152. This may
be made of %-inch gas pipe, with two
elbows and a T, as shown in the sketch,
the standard being sharpened by a black-
smith or by inserting a wooden point.
In the two elbows, which are about
four feet apart, there are cemented
short pieces of glass tube, or slender
phials, %-inch in diameter, with the
bottoms broken out, and provided with corks. To use
the instrument, the tube is filled with water colored with
bluing or ink, so as to show in the two tubes of
glass, when the arm is horizontal. By forcing the foot
Fig. 152.
Construction
of a
water-level.
470
Irrigation and Drainage
of the instrument into the ground until it stands firmly,
and removing the corks, the water will come to a level
at once, so that if the operator stands back about
four feet he may sight across the two surfaces to
determine diiferenees of level. If one uses this instru-
Fig. 153. Foiir forms of drainage levels, ■with target-rods.
ment with care, avoiding too long ranges, good work
may be done with it.
A carpenter's level is sometimes mounted in a
similar manner and used, but it is not as safe a
device, because the level itself is liable to be in error
Use of Drainage Levels 471
and there will be errors in deciding when it is set
exactly, whereas the water-level can never be in error,
and automatically adjusts itself at once, the only
chances for error being in taking the sights. Other
forms of drainage levels are represented in Fig. 153.
LEVELING A FIELD
If the field has but small fall, and is quite flat and
even, so that the inexperienced eye fails to detect the
direction of greatest slope, it will usually be safest to
check it into squares of 50 or 100 feet, driving short
stakes at the several corners, whose elevations may
then be determined. To do the leveling, set the
instrument at a, Fig. 155, midway between stations
I-l and 1-2, having first provided a notebook, ruled
as indicated in the table below. Turning the level
first upon I-l, its distance below the instrument is
read on the target -rod held upon that stake, and
the result, 4 feet, is recorded in the table in the
column headed "back-sight." The instrument is next
directed to 1-2 and its distance below the level found
to be 3.8 feet, which shows that its elevation must be
4 ft.— 3.8 ft.=.2 ft.
above that of station I-l. This reading of the target-
rod is entered in the column headed "fore -sight." In
the column headed "Elevation" the first station is
given arbitrarily a value of 10 feet, as is customary
to avoid minus signs, and on the same plan station
472 Irrigation and Drainage
1-2 will have an elevation of 10.2 feet, as stated in
the table.
Table giving data obtained in leveling field. Fig. 156
Station
I-l
1-2
1-3
1-4
1-5
1-6
II-6
ri-5
II -4
n-3
n-2
II- 1
in-i
III -2
111-3
III-4
III -5
ni-6
IV-6
IV-5
The level is now moved to h and the distance of
[-2 below it again measured and found to be 4.2 feet,
which is entered in the notebook under " back-sight,"
and the instrument turned upon 1-3, where the read-
ing is found to be 4 feet, and entered in the table.
The difference between the fore- and back-sights,
placed in the column headed " Difference," shows how
much higher one station is than another, and when
the first is added to the elevation above datum, 10
Back-sight
Fore-sight
Difference
Elevation
4
10
4.2
3.8
.2
10.2
3.8
4
.2
10.4
4
3.6
.2
10.6
3.9
3.8
.2
10.8
4
3.7
.2
11
3.8
3.98
.02
11.02
3.9
3.995
.195
10.825
4
4.095
.195
10.63
4.1
4.19
.19
10.44
3.9
4.26
.16
10.28
3.8
3.98
.08
10.2
4
3.6
.2
10.4
3.9
3.96
.04
10.44
4.2
3.775
.125
10.565
4.1
4.045
.155
10.72
3.8
3.93
.17
10.89
4.1
3.625
.185
11.075
4
4.185
.085
11.16
3.84
.16
11
Use of Drainage Levels
473
feet, at station I-l, it gives 10.2 feet, or the
elevation of station 1-2 above the same plane. The
difference, .2 feet, between stations 1-2 and 1-3 added
to the elevation of 1-2, gives 10.4 feet, or that of
station 1-3. In this manner the instrument is moved
forward step by step until measurements from e have
been made, when the level is next set at /, and back-
aud fore -sights taken and entered, as shown in the
table, so as to connect the observations of the first
line with those of the second line of stations.
Proceeding to g, the steps described are repeated
by moving back through h, i, j, k and I to m, and so
on until the elevations of all the stations have been
determined and entered in the table. It will be
Fig. 154. Method of leveling.
observed that when proceeding from higher to lower
levels it is necessary to subtract the value in the
column of differences from the elevation of the station
preceding it, in order to obtain the elevation of the
station for that difference.
In Fig. 154 is shown the method of leveling
described where the different positions of the level
and of the target along one line are shown in ele-
vation.
474
Irrigation and Drainage
LOCATION OF MAIN DRAINS AND LATERALS
After the notes of the field leveling have been
obtained, and the elevations computed from them,
these may be transferred to a diagram of the field, as
Fig. 155. Leveling for a eontotir map of field to te drained.
in Fig. 155, where they will show at a glance the'
slope of the surface, and where the mains must be
placed in order to secure the greatest fall, both for
them and for the laterals. It will be seen that station
VI -6 is the highest point in the field, while I-l is the
Location of Mains and Laterals
475
lowest, and that if a straight main were laid through
these two points it would be given the course along
which surface water would naturally flow, which is
also the direction of steepest slope.
The dotted lines in the figure are contours, or
X \ \ -^ X
• \ \ ^ X
X'^ \ \ ^^ \ \
X X liX X
^X \f \ \ -'
X V' \ X-^\
\ X \ N?X ^
\ / \ \^^ \
X ^\ V' \ \
X W \^^
=!^^\ X \ X
' \/ \ V X
' X X X
X X ^ X
X'"
A
\ix
X
X
X
X
X
10,9
10.6
/ X/'X >
' ' X X'
' ' X ^
' ' X / X
' ' ^v
O' CO' CO'
d\ S". S',
t.^^
f
Fig. 156. Arranging drains to secure the maxinrnm fall.
lines of equal elevation, and as in this case these
are circumferences of circles with centers at station
I-l, it is clear that the shortest distance between any
two contours will be measured along their radii, and
hence, that there also will be the greatest fall. Since
the diagonal line from VI- 6 and the lines I and 1
476 Irrigation mid Drainage
are each a radius of a circle from the same center,
I-l, the fall along each will be the] same, namely, 2.4
inches per 100 feet ; hence, to drain this piece of
land, three mains may occupy the positions of these
three lines, meeting at station I-l. But if laterals
are to be placed 100 feet apart, these could be given
about as great a fall if they were to connect with the
diagonal as a main, and take the positions indicated
by the two right -angle systems of lines in Fig, 155,
I, II, III, IV, V, representing laterals on the upper
side of the main, and 1, 2, 3, 4, 5 on the lower. If,
however, drains were to be placed 50 feet apart, then
the most rapid fall could be secured and the least
amount of tile would be required, by arranging the
laterals as shown in Fig. 156, where the same area
is represented with the contour lines drawn 100 feet
apart horizontally and .2 foot vertically, as they are
also in Fig. 155, and where the heavy ruling repre-
sents main drains and the light ones laterals.
STAKING OUT DRAINS
When the location of mains and laterals has been
determined, the next step in the practical work is
staking out the drains. There are various methods of
doing this, but one of the best is as follows : Short
stakes, about 8 to 10 inches long, called grade pegs,
are provided, and another set upon which records can
be made with lead pencil, longer than the others, and
called finders. With a tape line or chain and hatchet,
the work begins by laying off along the main, begin-
Laying Out Drains
477
ning at the outlet, intervals of 50 feet, at each of
which a grade peg is set about 12 iuches to one side
of the center of the ditch, where they will not be
disturbed, driving them down flush with the surface
of the ground. About 6 inches farther back from
the line of the ditch a finder is also set. Sub -mains
and laterals are staked off in a similar manner, and
when this is done the work of leveling for digging
the ditches may begin.
DETERMINING THE GRADE AND DEPTH OF
THE DITCHES
The determination of the levels of the grade pegs
should begin at the outlet of the main, and proceed in
the manner already described in leveling the field, enter-
ing the figures in a table prepared in the notebook,
as shown below :
Table showing field notes for determining depth, of ditch and grade of drain
Station
Back-sight
Fore-sight Difference
Elevations
Grade line
Depth of
ditch
Outlet
7
7
7
4
3
10
7
3
50
3.97
3.87
13
10.13
7.12
3.01
100
4.2
3.83
14
10.27
7.24
3.03
150
4.1
4.08
12
10.39
7.36
3.03
200
3.95
3.99
11
10.5
7.48
3.02
250
3.87
3.82
13
10.63
7.6
3.03
300
4 .
3.69
18
10.81
7.72
3.09
350
4.25
3,83
17
10.98
7.84
3.14
400
4.08
4.1
15
11.13
7.96
3.17
450
4.05
3.96
12
11.25
8.08
3.17
500
3.97
3.95
1
11.35
8.2
3.15
550
3.75
3.97
11.35
8.02
3.03
600
3.74
.01
11.36
8.44
2.92
478
Irrigation and Drainage
Referring to 157, which is a profile of the data in
the^table, A is the outlet of the drain; the first stake
set is marked 0, the second 50, etc., up to 600, the
numbers expressing the number of feet from the out-
let. The datum plane is chosen 10 feet below the
850 300 350 "O
550 600
tJSi^^g=-^7:'*_-Ja25£l.«4-r?.36r.^7.48.-:;-7.6UJi7.72^=- 7.81; ^7.96" ».08 ^S.20 *S.32 -i-S.«
Fig. 157. Detennining grade line and depth of ditch.
surface of the ground, at station 0, and the ground
here is 3 feet above the bottom of the drain, which
leaves the outlet 7 feet above datum, as stated in the
table, which is also the elevation of the grade line at
this place.
Referring to the table, in the column of elevations
it will be seen that the surface of the ground at 600
feet from the outlet is 11.36 feet above datum plane,
while the outlet is 7 feet above, making a total fall of
11.36—7 = 4.36 feet.
If it is decided to give the drain a fall of .24 foot,
Laying Out Drains 479
or 2.88 inches per 100 feet, it will be necessary to place
the bottom of the tile, at 600 feet from the outlet,
6 X. 24 = 1.44 feet
higher than the outlet; that is,
7+1.44 = 8.44 feet
above datum plane ; but as the surface of the ground
at the 600-foot station is 11.36 feet above this plane,
as given in the table, it is clear that the ditch must
be dug at this place
11.36 — 8.44 = 2.92 feet
deep, as written on the finder stake in Fig. 157, and
as given in the table of field notes in the column
headed "depth of ditch."
Since the grade line rises .24 foot per 100 feet and
.12 foot per 50 feet, the data in the table under
"grade line" are obtained by adding .12 foot to 7
feet, the distance of the outlet above datum, for the
50 -foot station ; twice .12 foot to the second or
100 -foot station, etc.
The numbers in the column of differences are
obtained hj subtracting the front -sight from the back-
sight, taken with each setting of the level, and these
differences, added to the height of the lower station,
give the elevation of the higher station above datum
plane, thus:
4 — 3.87 =.13 feet;
and this amount, added to the height of the back-
sight station, gives
10 + .13 = 10. 13 feet
as the elevation of the 50 -foot station, and subtract
480 Irrigation and Drainage
ing from this elevation that of the ^bottom of the
proposed ditch at this place, there is obtained
10.13—7.12 = 3.01 feet,
or the depth which the ditch must be dug at this
station, and it is the custom to write these depths on
the finder stakes, to serve as the guide to the ditchers
in digging, as represented in Fig. 157.
These values are given in feet and hundredths
rather than in feet and inches, because it is much-
simpler to make the calculations in this waj*. The
target -rod should be made to read in this way rather
than in feet and inches, and if the farmer makes his
own this may readilj' be done by first dividing the rod
into feet and then, taking a pair of dividers, set them
so as to space off ten equal divisions within each foot.
The tenths of a foot may then be subdivided in the
same manner into ten equal divisions, or hundredths
of a foot.
Where a level without a telescope is used, the
measuring rod should be provided with a sliding
target, as shown in Figs. 153 and 158, which may be
moved up and down by the target man, as directed, to
mark the elevation indicated by the instrument. The
best target is provided with an opening in front of the
rod, which permits the figures to be seen at the junc-
tion of the cross lines of the target.
In taking the elevations, the target -rod should
always be set upon the grade peg, and all subsequent
measurements in digging should also be made from
these pegs, which are driven in flush with the surface,
Changing Grade 481
not only that they may represent its true level, but
also to avoid danger of the pegs being disturbed.
MORE THAN ONE GRADE ON THE SAME DRAIN
It ver}^ frequentlj^ happens that the surface of the
land to be drained is such as to make it impracticable
to lay out the whole of a main or of a lateral with the
same amount of fall throughout. Let it be supposed
that at the end of the 600 feet represented in Fig.
157, the ground continued rising backward at a slower
rate for 500 feet more, as the figures show it had
begun to do, and that in the 500 feet the rise was
only six inches. In order to avoid digging too deeply
in some portions of the line, or of placing the tile too
close to the surface at others, it is necessary to change
the grade, and the new grade will be found by divid-
ing the total fall .5 feet by 5, the number of 100 feet,
which gives .1 foot, and half this amount instead of
.12, is what would be added at each 50 -foot station,
in order to get the new grade line elevations.
DIGGING THE DITCH
It has been pointed out that practice is required
in order to dig a ditch well, rapidly and easily. It is
further necessary to have suitable tools for the pur-
pose. First in importance is the ditching spade, two
forms of which are represented in Fig. 158. These
spades have blades 18 inches long, narrower than the
common tool, and strongly curved forward, to give
EE
482
Irrigation mid Drainage
greater stiffness, and to permit them to be thin and light.
The solid blade gives better satisfaction generally than
the other form shown in the cnt.
Besides the spade, there mnst also be the tile hoe,
or scoop, for cleaning out and grading the bottom of
Fig. 158. Some drainage tools.
the ditch, fitting it for the tile, different widths being
used for different tiles, as shown in the cut. Some of
these scoops are made with adjustable handles, per-
mitting the blade to be set at any desired angle, so
as to be used from the last spading of earth in the
ditch or from the top.
i'
\ '.,''■ ''-
■■■■■■■1
■ A •/' '^
■ i
r-
>
.--" vf iL^
"^v^S^^H
^RGlK^i^v^*^
^^K .:r '.
■Tr» •
...vV ■'
_.";;
• -. ^* ^-
^^^^ *•
-,.,"■***■»•-■
jj^K., --vil^aB
SB^&l
1^- ^^^\
• '^
ifr ^2»£tf
jH
^■"'^^iSB'^'
^^^H
Wp fc^.^:..-' :' ->
„:.i.-1W
B^H
1
^^^^^^1
RmI^^BI^'''
« JS
1^1
taa|gta|g«a
9l^^|
^
- 1
^^H|F' -'- --'' - ~"
T^^^^WH
^^^^^BHi^ '-^
■■^Bbk
liflH
Pv.
— - • f 1
"Jm^
^^^^e^A>-"^
^BBI
|H
Il
ri-aa iij^
K" .u.4,*^i_
^^^
^^^^^nfV^^'' ^, ^
Fig. 159. Commeneing a ditch.
i It;, luu. Kt-moviug the last two spadingsfroni the ditch.
Fig. 161. Bringing the ditch to grade line with tile hoe.
Fig. 162. Placing tile with tile hojk,
Digging the Ditch 485
When digging begins, a strong line is stretched
abont 4 inches back from the side of the ditch and a
narrow cutting made, seldom necessarily more than 12
inches wide, as shown in Fig. 159, the effort being to
remove as little earth as possible. The sides are cut
true to line to begin with, and maintained so to the
bottom, in order that a straight bed may be finished
to receive the tiles. When the ditch is deeper than
4 feet, it is necessary to make it a little wider at the
top but not much, as will be seen in Figs. 160 and 161,
where the first shows the men in line cutting a ditch
4.5 to 5 feet deep, while the second figure shows
another man following with the tile hoe, working from
the top, cleaning out the bottom and bringing it to
grade line. The line wdiich is seen in Fig. 161,
stretched along the ditch, is placed parallel with the
grade line some whole number of feet above it, and is
used by the man to measure from when finishing the
bottom. The line is a slender but strong cord, which
may be stretched tightly, so as not to sag. In the
ease in xiuestion, the man determined his depths with
the measuring rod in the foreground, his long expe-
rience enabling him to dispense with a sliding arm,
which is generally used, forming a right angle with
the rod and long enough to reach the grade line. In
Fig. 162, the last man is using the tile hook, shown
second from the right in Fig. 158, to lay the tile in
place. This ditch, although for 6 -inch tile, laid 4.5
to 5 feet deep, is scarcely more than 15 inches wide at
the top, as the length of the tile placed across the
ditch for a scale shows.
486 Irrigation and Drainage
These men never get into the bottom of the ditch, and
yet the tile are laid with great accuracy and. turned
about with the hook until close fitting joints are secured.
It is preferred by some to laj' the tile by hand,
the operator standing on the tile, which are covered
with earth 4 to 6 inches deep as rapidly as placed,
using the wet clay last thrown out, or some taken
from the side of the ditch, which is thoroughly
worked in about the tile, care being taken not to get
them out of alignment. By whatever method the tile
are laid, the greatest care must be observed in secur-
ing close joints and in covering them, to see that
they do not become displaced.
The work should begin at the outlet with the lay-
ing of the main, and proceed backward to the first
lateral, when this should be started and the junction
made at once, laying two or three tile of the lateral
before proceeding further with the main. If junction
tile are not used, the opening through the walls for
the connection is made with a small tile pick with a
sharp point, and great care should be taken to make
a close connection by shaping and fitting both pieces
together and covering the joint with stiff clay, well
packed about it.
If for any reason the line of tile is left, as at
night or over Sunday, the open upper end should be
plugged with a bunch of grass or covered with a
board, to prevent dirt being washed into the line in
case of rain. When the end of the line is reached,
the opening of the last tile should be closed with a
brick or stone.
Filli))g the Ditch
487
It is very inipoitaut to get the dirt well filled in
about the tile and at the same time well packed, in
order that large open water channels may not exist
through which streams of water may flow in sufficient
volume to carry silt into the tile through the joints,
and also in order that open channels may not exist
outside and under the tile along which streams may
gather and flow. The clay soil, usually last taken out
of the ditch, is the best for this purpose.
Fig. loy. The start und finish of tile draining
Various methods of filling the ditch, after the first
covering of the tile, are in use, and Fig. 163 repre-
sents one, where a plow is drawn by a team working
488 Irrigation and Drainage
on a long evener. Where a road scraper is available,
this makes a good tool for finishing up with after
the line is filled enough to cross with the team.
Another method of filling, where the work is done by
hand, is to tie a rope to the handle of a broad scoop,
which is worked by a man across the ditch, while
another guides the shovel as though not assisted bj'
the man with the rope. In this waj" the dirt is filled
in rapidly.
Still another method is to use a team on a wide
board scraper provided with handles, drawing it toward
the ditch, the team being attached by means of a long
rope and working on the opposite side of the ditch,
the filling being done by driving forward and then
backing, the man holding the scraper pulling the tool
back.
When quicksand is encountered in laying tile, it
may be necessary to brace the sides of the ditch to
prevent caving, when digging. This may be done by
driving sticks in between two pieces of board, thus
holding them against the opposite sides of the
ditch. It is occasionally true that the bottom is so
soft from quicksand that the tile cannot be laid to
gi-ade, and in such cases a fence board may be
placed on the bottom and the tile laid upon this.
In other cases the ditch may be dug a little below
grade line, and the bottom covered with clay, if that
is available, so as to form a foundation upon which
to place the tile. It will sometimes be true that a
quicksand spot will become sufficiently firm to lay
across if it is permitted to drain three or four days,
Cost of Underdraining 489
and the level of the ground water be thus lowered.
The reason for this is that the quicksand character
is due to the water being forced up through the fine
sand, which has little adhesion between its grains,
and the water tends to float the sand, thus causing it
to run with unusual freedom ; but when the water is
given time to drain away, so that the sand is no
longer full of it above the bottom of the ditch, it
becomes firm, and the tile maj- then be laid.
COST OF UNDERDRAINING
It is not possible to give the cost of draining land
without knowing all of the details which go to make
up the total expense ; but certain general statements
maj' be made, which will enable any one to compute
for himself what the cost is likely to be.
In the case represented hy Figs. 159 to 163, the
work was done by a professional drainage euginee]* at
an average cost of $3 per 100 feet for digging and
laying the tile, and 30 cents per 100 feet for filling
the ditches, thus making the labor after the tile had
been placed upon the ground $3.30 per 100 feet,
including the board of the men. The ground drained
in this case was such as to represent about average
conditions, where the spade may be readily put into the
soil with the pressure of the foot, where no stones or
quicksands are encountered, and where the main has
a depth of 3 to 5 feet, and the laterals an average
depth of 3 feet. In the case represented in Fig. 141,
Mr. Elliot gives the cost of the different items as
expressed in the table which follows:
490 Irrigation and Drainage
Cost of main drains per 1,000 feet
No. of feet Size
Depth
Digging, laying
Tile and filling Total
Cost '
per rod
1,000
2,700
850
7 in
6 in.
5 in.
5 ft.
5 ft.
4 ft.
Cost
$60.00 $37.20
40.00 36.60
30.00 24.20
of lateral drains
$97.20
206.82
46 07
$1.60
1.26
.89
8,280
7,030
4 in.
3 in.
Total. . .
3.5 ft.
3 ft
$20.00 $20.00
13.20 20.00
$331.20
233.40
$914.69
$0.66
.55
It will be seen from this table that the cost of
draining 80 acres, as represented in the figure, averaged
$11.43 per acre where everything was counted. It
will be seen that the cost of mains was from two to
three times as much as laterals of 3-inch tile, and
hence, that the larger and longer the mains must be
made the more expensive relatively the draining will be.
Cost of mains per 100 feet
5 -inch
G-ineh
7-inch ■
8-ineh
(
)th of ditch
Ilost of digging
and laying
(
Cost of tile
Jost of fillin
ditch
ig Total cost
per 100 feet
3 feet
$1.50
$3.00
$0.30
$4.30
4 feet
2.00
3.00
.42
5.42
5 feet
3.00
3.00
.60
6.60
6 feet
4.50
3.00
.75
8.25
3 feet
1.50
4.00
.30
5.80
4 feet
2.10
4.00
.42
6.52
5 feet
3.00
4.00
.66
7.66
6 feet
5.10
4.00
.78
9.88
3 feet
1.80
6.00
.36
8.16
4 feet
2.40
6.00
.48
8.88
5 feet
3.00
6.00
.72
9.72
6 feet
5.70
6.00
.90
12.60
3 feet
1.92
8.50
.42
10.84
4 feet
2.58
8.50
.54
11.62
5 feet
3.90
8 50
.78
13.18
G feet
6.00
8.50
1.00
15.52
Peat Lands 491
We quote this table regarding the cost of mains,
as estimated by Mr. Elliot, where the price paid for
good ditchers is $2 per day; but in this estimate the
board of the men is not included, neither is the cost
of hauling the tile from the station to the field.
This same writer estimates the cost of 3 -inch lat-
erals, placed 3 to 3.5 feet deep, at $2 per 100 feet for
the digging, laying and filling, and tile at the present
writing would add another dollar, making $3 per 100
feet, not including board or hauling the tile.
The cost per acre will, of course, vary with the
distance between lines of tile, and will increase very
nearly in proportion to the number of feet of tile
used.
PEAT LANDS
There are many marshes underlaid by beds of peat
not yet well rotted ; peat so free from silt and so
fibrous in texture that when dry it could be used for
fuel. Where fields are underlaid b}^ such beds having
a depth of three or more feet, they are not likely to
become at once productive if well drained. On the
other hand, where the peat deposit is only from 6 to
18 inches deep, there are likely to be better returns
from thorough drainage.
In the first class of cases referred to, underdrain-
ing is not usually to be recommended as the first
step toward improvement. The difficulty lies in the
fact that when peat beds are drained they shrink
greatly in volume, thus lowering the surface in a
492 Irrigation and Drainage
marked degree, and if underdrains were laid at once,
the lines of the tile would ultimately be found too
close to the surface. It is, therefore, usually better
in such cases to drain first with open ditches, plac-
ing them where ultimateh^ they may be deepened
and converted into underdrains. The surface ditch-
ing will dry out the marsh to a considerable extent,
and permit the needed decay and shrinkage of the
peat to take place, although several years may be
required for this.
If the peat is very coarse and thick, and if little
vegetation grows upon it, it ma}' be well to burn it
over several times when not too dry, in order to
increase the silt and ash in the soil and to hasten
the shrinkage. The ash thus formed will so much
improve the texture of the surface as to very mate-
rially assist in getting a crop started upon the area.
It is very important to get a crop started upon the
soil as soon as practicable, because this greatlj" facili-
tates and hastens the rate of decaj'. This should
be done, even though it may not be remunerative in
any other way than that of improving the texture of
the soil.
INDEX
Acre-foot, 239.
Acre-inch, 239.
Aermetor, windmill, 313; pump, 316.
Air, in the soil, 7, 182; humidity, 40, 44,
50; required by clover, 49; by corn,
185; interferes with percolation, 333;
need of in soil, 182, 370, 418; lack of
in puddled soil, 334: changes in tem-
perature and pressure influence ven-
tilation, 420.
Alfalfa, roots, 233; irrigation, 237, 346,
348 ; utilizing waste water, 379.
Algeria, irrigation, 85, 238 ; duty of
water in, 212; artesian wells, 85.
Alkali, composition, 278; accumulation,
223, 266, 270, 272, 274, 284; cause of in-
jjiries, 270, 416; accumulation by in-
tensive farming, 274, 284; amounts in-
jurious, 275, 278; develops soonest in
clay soil, 286 ; correction by land
plaster, 280, 284, 287; distribution in
soil, 282; influenced by tillage, 284;
influenced by roots, 284; cause of
abandonment of ancient irrigation
systems, 289; geographical distribu-
tion, 272; formed by canal seepage,
294 ; soils which soonest develop
alkali, 286; cause of puddling, 335.
Alkali lands, 269, 416; alvim spots, 269;
soluble salts, 269, 276 ; character of
vegetation, 281; land plasters, 280, 284;
improvement by drainage, 223, 284,
288; ultimate remedy drainage, 288.
Alkali salts, 266; kills barley, 276; see
Alkali.
Alkali water, unsuitable for irrigation,
266, 284, 285; correction before use,
287.
Alum spots, 269.
Animal power for irrigation, 328.
Ants, work in soil ventilation, 419.
Apple, roots, 231.
Argentina, irrigation,'87.
Arid climate, efficiency of rainfall, 4,
104; accumulation of alkalies, 272.
Armenia, irrigation, 84.
Artesian wells, in Sahara, 85; in Ha-
waii, 86.
Assyrian irrigation, 67.
Australia, irrigation, 81.
Austria-Hungary, irrigation, 75.
Baker, J. 0., 466.
Barker, P. C, 236.
Barley, water used, 21, 24, 34, 46, 235
available rainfall, 124 ; yield, 129
jield increased by irrigation, 110
second crop, 130, 179; number of irri-
gations, 235; on alkali lands,'276.
Barrens, 114.
Basin irrigation, 387, 390 ; Egypt, 288.
Bavaria, irrigation, 76.
Bear valley dam, 302.
Belgium, water-meadows, 362.
Blackberry irrigation, 383.
Black marsh soil, mulches, 201; alkali,
269, 273; vegetation, 281.
Boussingault, 49.
Breathing of plants, 47, 182; pores, 51.
Bucket pump, 316, 319, 325.
Busca canal, 210.
Cabbage, irrigation, 387 ; yield in-
creased by irrigation, 110; effect of
supplementing rainfall in Wisconsin,
175.
(493)
494
Index
Canal, ancient, 67; Busea, 210; Ceylon,
81; Doab, 80; Egyptian, 68; Eu-
phrates, 68; Forez, 72 ; Gattinara,
210; Great Imperial, 71; Ganges sys-
tem, 80; India, 79 ; Indus valley, 81;
Ivrea, 209; West and East Jumna, 80;
Kern Island, 292 ; Nahrawan and
Dyiel, 69; Nira, 78 ; Santa Ana, 297;
Sirhiud,291; Soane circle, 80; cement,
300, 412 ; dangers, 295 ; sewage, 410,
412; stone, 410.
Canvas dam, 339, 341, 355.
Cape Colony irrigation, 85.
Capillary spread of water, 101, 330, 375.
Capillarity, rate in sand and loam, 148.
Carbon dioxide, consumed by clover,
49 ; possible insufficiency in close
planting, 185; in soil ventilation, 419;
consumed by maize, 185.
Carpenter, L. G., water-meadows, 219;
seepage from reservoir, 323 ; water
divisor, 245.
Catch crops, 152.
Celery, irrigation, 385.
Ceylon, irrigation, 81.
Checks, 345, 348, 350.
Check ridges, 346, 348.
Child, J. T., 83.
China, irrigation, 71, 82.
Chinese irrigation, 387.
Clay soil, develops alkali, 286.
Climate, arid, 4, 104; for irrigation
practice, 89; for sewage irrigation,
404; lainfall needed for humid and
subhnmid, 121.
Clover, water used, 24, 34, 36, 41, 46 ;
irrigation, 110, 130, 179 ; on sandy
soil, 169.
Colmatage, 94, 261.
Corn. See Maize.
Cotton, duty of water, 211.
Craigentinny meadows, 16, 92, 254, 403.
Cranberries, duty of water, 220; irriga-
tion, 365.
Cranefield, F., irrigation with cold
water, 251.
Crops, yields, 125, 126, 174, 175, 177, 179,
187, 190, 216 ; for sewage irrigation,
409, 411.
Cucumbers, irrigation, 388.
Cultivation. See Tillage.
Cultivator, orchard, 381; potatoes, 354.
Croyden, sewage irrigation, 411,412, 413.
Dam, submerged, 305; canvas, 339, 341,
355; Bear valley, 302; Vir weir, 78.
Deherain, 276.
Delaware river water, 252.
Deuitrifieation, 334, 370; in sewage, 403;
lessened by drainage, 420.
Denmark, irrigation, 75.
De Vries, 277.
Divisors, 244.
Ditches, depth and grade, 477; bringing
to gi'ade, 484 ; digging, 481 ; com-
mencing and flnishing,483 ; filling, 487.
Doon, for lifting water, 328.
Drainage, principles, 415 ; influence on
fertility, 13; remedy for alkali lands,
284, 288; made necessary by .seepage
from canals, 295; of water-meadows,
360, 364; of cranberry marshes, 366,
368; rice fields, 369, 371; necessity,
416; ventilates soil, 418, 419; lessens
denitriflcation, 420; increases avail-
able moisture, 13, 422 ; makes soil
warmer, 423 ; where needed, 428 ;
sinks and ponds, 460 ; intercepting
underflow, 459; intercepting surface
water, 461; use of trees, 462 ; use of
windmill, 463; levels, 470; tools, 482;
peat lauds, 491.
Drainage levels, 470 ; use, 471, 473, 477.
Drainage, sixrface, 464, 466.
Drains, depth, 436, 442 ; distance ap.irt,
437, 439 ; used in sub-irrigation, 400;
entrance of water, 438, 445 ; kinds,
443 ; rate of entrance of water, 446 ;
use of collars, 446 ; fall or gradient,
447 ; size of mains, 450, 452 ; size of
laterals, 450, 452 ; outlets, 453 ; ob-
structions, 455 ; laying out systems,
Index
495
456 ; cost, 458, 489 ; staking out, 476 ;
determining depth and grade, 477 ;
changing grade, 481 ; in peat lands,
491; surface, 464, 466.
Drill, seed, 167.
Drought, frequency and length of pe-
riods, 106, 108, 109, 126.
Durance, fertility of water, 260 ; head-
gate, 263.
Duty of water, 212, 213, 214, 236 ; maxi-
mum, 196 ; least amount for paying
crop, 95; average, 214 ; highest prob-
able, 198,215; influenced by crop, 199,
227 ; influenced by soil, 200, 203 ; in.
flueneed by rainfall, 204 ; influenced
tby subsoil, 205; influenced by cultiva-
tion, 206 ; influenced by closeness of
planting, 207; influenced by fertility,
207 ; influenced by frequency of wa-
teriug, 207 ; in Egypt, 211 ; France,
211; Italy, 209; Spain, 211; for sugar
cane, 214 ; rice, 217; for water-mead-
ows, 219 ; for cranberries, 220 ; in
sub-irrigation, 396, 400.
Drj' farming, western United States, 100.
Dykes, 261, 306, 366, 369, 428 ; sluices
373.
Earthworms, in soil ventilation, 419.
Ebermayer, temperature in germina-
tion, 248, 425.
Edinburgh, sewage irrigation, 92, 254,
403; Evening Dispatch, 257.
Egypt, irrigation, 67, 84, 260, 262, 328 ;
duty of water, 211 ; prevention of
alkali, 288.
Elliott, C. G., 450, 451, 489, 490.
England, irrigation, 76, 360, 409, 411,
413.
Euphrates, canals, 68.
Evaporation, from plants, 40, 42 ; from
clover field, 50; rate from soU, 98,
148 ; from rolled ground, 167 ; in-
influenced by windbreaks, 169 ;
through mulches, 201.
Fallowing, relation to soil moisture,
153, 162, 163, 223.
Fertility, influenced by drainage, 13 ;
by cultivation, 370 ; affects duty of
water, 207.
Fertilization, by irrigation, 16, 92, 2"!,
259.
Fertilizers, in sewage, 404; in river wa-
ter, 252, 253, 259, 260.
Field irrigation, by tlooding, 338, 345 ;
in checks, 347, 350 ; by furrows, 352,
354, 358; sub-irrigation, 399.
Filtration of sewage, 404.
Flume box, 375.
Flynn, duty of water, 212.
Flooding, 338; dry soil, 333 ; danger of
puddling, 335; systems, 340 ; by run-
ning water, 340; on steep slopes, 342;
permanent meadows, 344 ; in checks,
345, 347,350; preparatory to planting,
353; to prevent frost, 365; to destroy
insects, 365; rice fields, 369; to germi-
nate red rice, 371; orchards, 383; gar-
dens, 386, 390; lawns and parks, 392.
Foot ditch, 378.
Foote, A. D., spUlbox, 245.
Forez canal, 72.
France, irrigation, l72 ; duty of water,
211; water-meadows, 219.
Fruit, irrigation, 383.
Furrows, capillary spreading, 161, 330 ;
distance apart, 336 ; gradient, 338 ;
distributing, 340, 342.
Furrow irrigation, 352, 358; on sandy
soil, 330 ; on fine soil, 332 ; puddles
soil less, 336; on steep slopes, 338 ;
for potatoes, 354 ; in alternate rows,
354, 357 ; for bed flooding, 359 ; for
orchards, 375; ring-furrows, 380 ; for
small fruits, 383 ; for gardens, 385,
387, 389 ; for melons, 388 ; requires
less water, 387.
Garden, irrigation, 384; sewage garden,
407.
Gas-engine, 324; cost of ninniug, 324.
496
Index
Gasoline engine, 305, 324, 393 ; cost of
running, 324.
Gasparin, ratio of grain to stra'w,l96 ;
salt in soil, 276.
Genne^Tlliers, sewage irrigation, 389,
411; model gardens, 408 ; sewage hy-
drant, 410 ; stone canal, 410 ; health-
fiilness, 413.
Gipps, F. S., 66.
Goff, E. S., irrigation of strawberries,
181: depth of roots, 231.
Goodale, G. A., 51.
Goss, Arthur, 253, 259.
Grade pegs, 478.
Grader, 350, 351, 352.
Grading for irrigation, 346, 348, 351.
Grain, irrigation, 340, 342, 344, 346 ; dry
farming, 103 ; harrowing and rolling,
146 ; thin seeding, 163 ; duty of water,
198.
Grapes, roots, 232; frequency of irriga-
tion, 238.
Grass, observed yields, 127; on sewage
meadows, 92, 409; on water-meadows,
219 ; irrigation, 340, 342, 346 ; in lawns
and parks, 392.
Gravel, silted, 263.
Greeley, Colorado, irrigation of grain,
340 ; potatoes, 354.
Green manure, 151.
Ground-water, origin, 429 ; relation to
surface, 431, 435 ; lines of flow, 432,
438 ; discharge into streams, 433 ;
gradient, 435; changes in level, 440.
Growth of river, 433.
Grunsky, C. E., 292, 349.
Hall, Wm. H., 211.
Hare. R. F., 253.
Harrington, M. W., 99.
Harvey, F. H., 309.
Hawaii, irrigation, 86 ; duty of water
for sugar cane, 214.
Hay, yields, 127, 178 ; need for irriga-
tion, 128 ; second crop, 130, 179 ; duty
of water, 215.
Hazzard, W. M., rice irrigation, 238.
Health, influence of sewage, 256, 295,
Hellriegel, 96. {413.
Hilgard, E. W., peculiarities of arid
soUs, 6, 229 ; alkali lands, 269, 276 ;
composition of alkali salts, 278 ; land
plaster for alkali lands, 280,284; roots
in arid soils, 6, 229.
Hinton, R. J., 78, 81.
Hollis, Geo. S., 85.
Humidity of air, 40, 44, 50.
Hunter, intertillage, 157. [410.
Hydrants, distributing, 301 ; sewage,
Hydratdie rams, 310.
Inch, acre, 240; miner's, 241. [291.
India, irrigation, 77, 328; Sirhind canal.
Insects, destroyed by irrigation, 218, 221.
IntertUlage, 157.
Irrigation culture, 66.
Irrigation, antiquity, 66; extent, 72; ob-
jects, 91; cHmatic conditions, 89; fre-
quency, 107, 212, 223, 234, 236 ; insuf-
fiency of water, 117; amount of water,
196, 208, 212, 213, 214, 236 ; late crops
difficult to grow without, 129 ; in-
crease of yield in humid climates, 171;
closer planting possible, 181 ; tUlage
as a substitute, 117 ; character of
water, 248 ; temperature, 248 ; num-
ber of irrigations required, 235; fer-
tilizing value, 251 ; supplying water,
290 ; methods of application, 329 ;
sewage, 403.
Italy, irrigation, 71, 359; duty of water,
209, 219 ; water-meadows, 219 ; mar-
cite, 219 ; sewage, 220.
Ivrea canal, 209.
Japan, irrigation, 82.
Java, irrigation, 86.
Kansas, yields of grain, 103; rainfall,
103.
Kern Island canal, 292.
Kiihn, Jul., 454.
Index
497
Land plaster, for alkalies, 280, 284, 287.
Laterals, subdivision, 223; length and
size, 452 ; outlet, 454 ; junction, 464;
cost, 490.
Lawn, irrigation , 391 ; eostof plant, 393 ;
method, 395.
Laveleye, E., 75.
Leaching, 222; may assist nitrification,
12; prevents alkali, 223, 284, 288; nec-
essary, 275.
Leveling, methods, 471, 473, 477.
Levels, methods, 469; instruments, 470.
Lois Weedon, system of intertillage,157.
Lombardini, 260.
Lombock, irrigation, 87.
Lettuce, irrigation, 385.
Lew Chew, irrigation, 83.
Loughridge, R. H., 229.
Madagascar, irrigation, 86.
Madeira, irrigation, 86.
Maeris, Lake, 66.
Mains, 451, 457; size, 451; length, 452;
cost, 490.
Maize, water used, 21, 24, 38, 39, 41, 46,
60, 177, 234 ; flint and dent, 40, 184;
roots, 61, 160; yields and rainfall, 109;
yield increased by irrigation, 110, 177;
observed yields, 126, 177, 190; varia-
tion of yield with soil moisture, 144;
rain of growing season, 124 ; maxi-
mum limit of yield, 187; need for air,
182,185; clo.se planting, 184,193; yields
with varying closeness of planting,
190; duty of water, 211, 215 ; frequency
of irrigation, 235.
Mangon, water on water-meadows, 219.
Mareite, 219.
Marktis, E., duty of water, 203.
Meadows, water, 16, 92, 219, 251, 359;
Craigentinny, 16, 92, 254, 403; English,
76, 360; Italian, 362; Belgian, 362;
mountain, 365; mareite, 219; duty of
water, 219; sewage, 220, 254; mulch-
ing, 146; irrigation, frequency, 237.
Measurement of water, 239; units, 239;
methods, 241; by time, 242; subdivi-
sion of laterals, 243 ; with divisors,
244; modules, 245.
Melons, irrigation, 388.
Milan, sewage irrigation, 220.
Milk, from sewage grass, 256.
Miner's inch, 241.
Mississippi, annual discharge, 117.
Modules, 245; spill-box, 245.
Mulches, 145; of soil, 142; effectiveness
in arid climates, 104; lose effective-
ness, 145, 164; for meadows, 146; in-
fluence of depth, 147, 206; vary with
kinds of soil, 201; prodiietion after
irrigation, 381.
Neerpelt, water-meadows, 362.
Newell, F. H., irrigation, 88; dry farm-
ing, 102; run-off, 119.
New Jersey, water analyses, 252.
New Mexico, frequency of irrigation,
238.
Nile, irrigation, 67, 84, 262, 288; daily
discharge, 85; delta, 08; sediment in
water, 260.
Nitrates, in artesian waters, 85 ; in
river water, 2.52; in sewage, 404.
Nitrification, in arid soils, 7; needs wa-
ter, 11 ; influenced by drainage, 13,
420 ; effect of tillage, 149, 163, 165;
needs oxygen, 183, 334, 370, 418.
Nitrogen-fixing tubercles^ 233.
Oats, water used, 21, 24, 31^41, 46; rain
of growing season, 124; yields, 126;
water needed, 215.
Oranges, frequency of irrigation, 238;
furrow irrigation, 374.
Orchards, irrigation, 338, 373; frequency
of irrigation, 238; ring furrows, 380;
cultivator, 381; cultivation, 381, 383;
sub-irrigation, 398.
Osmotic pressure, 63.
Pajcottah, 327.
Palms, irrigation, 85.
4.98
Index
Park irrigation, 391.
Pecas, water used, 46.
Peat lands, 491; warping, 262.
Percolation of water, 225 ; through
sand, 113, 205; on duty of water, 203;
through shrinkage cracks, 227 ; into
tile, 446; loss, 330; rate from tile, 400.
Perels, E., duty of water, 203, 212.
Persian wheel, 325, 328.
Peru, irrigation, 71.
Phcenieian irrigation, 69. [299.
Pipe line, Redlands, 290; redwqod, 298,
Pipes for lawns, 394.
Plaguiol, salt in soils, 275.
Plant breathing, 47.
Plant feeding, 52, 57.
Plant-food, 14, 15, 93, 252, 259; developed
by tillage, 149; effect of fallowing,
1.54; in alkali salts, 280, 285.
Plant-house experiments, 18, 35, 43;
yields, 25, 41.
Plowing, fall, 131; plowing under green
manure, 151; to form check ridges,
346.
Plow, for producing mulch, 149 ; for
producing distributing fiu-rows, 340,
342. [260.
Po, irrigation, 72; sediment in water,
Potatoes, irrigation, 28, 32, 35, 172, 353,
357, 413; water used, 30, 37, 46, 174-
237; yields, 110, 357; advantages of
irrigation in humid climates, 172 ;
watering alternate rows, 354, 357 ;
distance between rows, 357; moisture
in rows, 161, 200; duty of water, 215;
number of waterings, 237, 356.
Press drill, 167.
Puddling of soils, principles governing,
334.,
Pumping, with windmill, 313, 316; with
engines, 324; cost, 324, 326; for cran-
berries, 368; for drainage, 463.
Pumps, with windmill, 316, 319; with
engines, 324, 326, 393; with water
wheels, 76, 306, 308, 309; with horse
I)Ower, 325,
Quicksand, 488.
Rainfall, in arid and semi-arid climates,
4, 0, 99, 101; timely, 10; of irrigated
countries, 89; in Kansas, 103; fre-
quency in Wisconsin, 108 ; like
amounts not equally effective, 101,
115, 204 ; relation to yield, 109, 125 ;
conditions modifying effectiveness,
110; in United States, 123; in eastern
United States, 124; amount needed in
Iramid regions, 121; of growing sea-
son, 124 ; distribution in time \\u-
favorable to maximiim yields, 125;
early rains saved by tillage, 128; af-
fects duty of water, 204; in Colorado,
236; in India, 291.
Ramming engine, 310.
Rape, ii'rigation, 359.
Raspberries, roots, 231; irrigation, 383;
sub-irrigation, 398.
Read, T. M., solids in river waters, 253.
Redlands, Cal., irrigation systems, 296.
Red rice, 371.
Reservoir, distributing, 297; construc-
tion, 320; sluice, 321; circular, 322;
seepage and evaporation, 323; capac-
ities, 323; for cranberries, 367; use in
drainage, 464.
Rice, irrigation, 368; in Italy, 210; in
Egypt, 211; South Carolina, 238, 266,
306, 369, 372; duty of water, 217; fre-
quency of irrigation, 238 ; cultiva-
tion, 370; red rice, 371; upland, 373.
Ridge cultivation, 165.
Rio Grande, analyses of water, 253, 259.
Road grader, 3.50.
Rolling in relation to soil moisture, 166;
cause of loss of moisture, 167.
Roman canals, 70.
Root cap, 64.
Root hairs, 55; relation to soil grains,
55; acid reaction, 59.
Roots, depth of penetration in arid
soils, 6, 229; shallow in undrained
soil, 13; function, 55; absorbing sur-
Index
499
face, 55; acid reaction, 59; extent of
surface, 59, 61, IGO ; movement
through soil, 63; siiperficial develop-
ment, 208; depth, 200, 227, 231; oats,
clover and barley, 60; maize, 61;
prune, 228; apple, 229; grape, 230;
raspberry, 231 ; strawberry, 232 ;
alfalfa, 233. [119.
Run-off, Mississippi, 117; United States,
Rye as green manure, 151.
Rye gi-ass, for sewage meadows, 409.
Sachs, 55, 425.
Sahara, irrigation, 85.
Salts, soluble in alkali land, 269, 276;
cause of injuries, 270 ; accumulate
with intensive farming, 274 ; amount
injurious, 275, 278.
Saltwirt, 276.
Sandwich Islands, irrigation, 86; duty
of water, 215.
Sand, percolation, 112, 224.
Sandy soils, experiments, 32; texture
Improved by irrigation, 93, 262; re-
tain little water. 111, 205, 224 ; why
unproductive, 114; destructive effects
of winds, 168; areas suited to irriga-
tion, 264; furrow irrigation, 330, 358;
handling water, 331.
San Joaquin valley, 4, 96, 98; flooding
system, 348.
Scraper, ridging, 348, 351.
Seaman and Schuske, bucket pump, 316.
Second-foot, 239.
Seed-bed, preparation, 150, 167.
Seepage, coarse soils, 203; upland rice
culture, 218 ; from canals, 244 ; from
reservoirs, 323.
Sewage, dangerous nitrogen com-
pounds, 405; agricultural value, 406;
need of wider agricultural use, 406,
409 ; in Italy, 406 ; Edinbm-gh, 403 ;
Milan, 407; Pai-is, 407; Croyden, 411,
412, 413.
Sewage effluent, purity, 414; bacteria,
414.
Sewage grass, wholesomeness, 256, 413.
Sewage irrigation, object sought, 403;
Craigentinny meadows, 16, 92, 254;
healthfulness, 256, 405, 413; distri-
bution of water, 403; climatic condi-
tions favorable, 404; report of Mas-
sachusetts State Board of Health,
405; soils best suited, 406; oppor-
tiinity for in United States, 407;
model garden, 407; yield of grass, 409;
grasses for, 409; crops, 409, 411.
Sewage purification, 405; by irrigation,
405; by filtration, 404; essential con-
ditions, 405.
Sewage water, 15, 92, 220, 253.
Siam, irrigation, 83.
Silt basin, 448.
Silting coarse soiis, 93, 260, 261; oppor-
tunity for in United States, 264; of
rice fields, 370.
Siphon, in pipe line, 296; elevator, 310.
Sirhind canal, 291.
Shiiee, for reservoir, 261, 321, 369.
Small fruits, irrigation, 383; late plow-
ing, 132.
Smith, Baird, duty of water, 209 ; water-
meadows, 220.
Smith, Rev., system of intertillage, 157.
Smith, Brothers, irrigation plant, 308.
Soil, water capacity, 3, 224; texture in
relation to rainfall, 3; humid and
arid, 4; ventilation, 11, 419; water-
logging, 11, 334; sandy, 32, 111, 114,
168, 205, 224, 264, 330, 331, 358; silt-
ing, 93, 260, 262, 263, 264; mulches,
201, 206; black marsh, 201, 281; pore
space, 63; best temperature, 248;
alkali, 282; clay, 286; puddling, prin-
ciples governing, 334, 335 ; washing,
principles governing, 337 ; absorp-
tion of sewage, 404 ; kinds best
suited to sewage irrigation, 406.
Soil grains, relation to root hairs, 55;
relation of size to drainage, 438.
Soil mulches, 142; more effective in
arid climates, 105; effectiveness, 144,
500
Index
201 ; lose effectiveness, 145 ; of dif-
ferent soils compared, 144, 201 ;
depth, 147, 165, 206; frequency of stir-
ring, 164.
Soil moisture, advantages of abundant
supply, 9; mechanism of plant sup-
ply, 54; effect of subsoiling, 134; ef-
fect of fallowing, 153, 155, 162, 225; in
potato rows, 161; means of conserv-
ing, 131; conservation by tillage, 164;
influence of rolling, 166; loss through
mulches, 144, 201; best amount, 226.
Soil ventilation, 419; need, 11; work of
carbonic acid, 419; infliience of drain-
age, 418; part played by roots, 420,
421; influence of changing air tem-
perature and pressure, 420; may les-
sen denitriflcation, 420 ; may increase
nitrates, 420; may be too thorough,
421.
Soil temperature, 248, 250, 425; in-
fluenced by drainage, 423 ; importance,
425 ; influence on germination, 425 ;
influence of cultivation, 427.
Soil warmth, 425.
Soil water, plant-food dissolved, 14 ;
amount of alkalies carried, 278; stag-
nation prevented by drainage, 416.
South America, irrigation, 87.
South Carolina, rice irrigation, 238,
266, 306, 369, 372.
Spain, irrigation, 72, 238 ; duty of water,
211.
Spill-box, 245.
Spraying lawns, 393.
Strawberries, irrigation, 110, 181, 384 ;
roots, 232; sub-irrigation, 398.
Storer, P. H., 254, 275.
Sub-irrigation, 396; of clover, 179 ; ob-
jections and difficulties in the way,
396, 397, 401 ; water-meadows, 401 ;
orchards and small fruits, 401 ; dan-
ger of clogging tile by roots, 401 ;
time required, 401 ; throiigh tile
drains, 400; conditions necessary, 401;
an adjiinct to drainage, 460.
(Subsoil, affects duty of water, 205.
Subsoiling, 133 ; effects, 139 ; sugar
cane, irrigation, 214 ; duty of water,
215.
Summer fallowing, 153, 154, 163.
Sunlight, evaporation during, 44; action
in plant-feeding, 49; limited in close
planting, 183, 194.
Surface drainage, 464 ; examples, 466 ;
peat lands, 491.
Surface tension, 57.
Swamp lands, 273 ; area in United
States, 415 ; improved by drainage,
416; intercepting underflow, 459; in-
tercepting surface water, 461;
Switzerland, irrigation, 74, 365.
Target-rod, 470, 471.
Temperature of soil, 248 ; subsoil
changed by rains and irrigation, 14,
248 ; redviced by close planting, 183 ;
favorable to sewage irrigation, 404.
Temperature of water for irrigation,
250.
Tidal irrigation, 238, 261, 306, 369, 373.
Tigris, canals, 69.
Tile, injurj' by frost, 442 ; for sub-irri-
gation, 398,400; size, 449, 452; laying,
484; in quicksand, 488.
Tile-hook, 482.
Tillage, extent to which it may replace
rain or irrigation, 117 ; most which
may be hoped for tillage, 120 ; inap-
plicable in some cases, 127 ; chiefly
saves early rains, 128; may do harm,
129 ; late plowing, 132 ; subsoiling,
133 ; earth mulches, 142, 164, 206 ;
mulches lose in effectiveness, 145 ;
harrowing and rolling, 146, 166; early
tillage important, 148 ; plow as a til-
lage tool, 149 ; intertillage, 157, 163 ;
frequency of tillage, 164, 205 ; depth,
165, 206 ; ridged and flat cultivation,
165 ; in rice fields, 370 ; after irriga-
tion, 381, 389 ; with orchard cultiva-
tor, 381.
Index
501
Time as a unit for division of water,
242.
Transpiration, greatest during sun-
shine, 45, 46 ; need of water, 50 ;
mechanism, 46; method, 46 ; control'
53.
Tulare Exp. Station, 276.
Tiill, Jethro, system of intertillage, 157.
Turljiue wheel, 308.
Underdrainiug, practical details, 467 ;
• cost, 489; peat lands, 491.
Underflow, intercepting, 459.
Underground water, diverting for irri-
gation, 304.
Units of water measiu-ement , 239.
Vegetables, garden irrigation, 385.
Ventilation of soil, 419. See soil venti-
lation.
Vir weir, 78.
Vosges, water-meadows, 219.
Warping, 94, 261.
Washing of soil, principles governing,
337.
Washington, dry farming, 100 ; rainfall,
101, 204.
Water, apparent greater service in arid
climates, 5, 104; need for nitrifica-
tion, 12; fertilizing value, 14, 93, 251-
259; only one of the necessarj- plant
foods, 15; amount used by crops, 16
21, 24, 30, 36, 37, 38, 39, 41, 46, 60, 97, 122,
160, 174, 177, 215; variations in amount
used by crops, 39; \ised in transpira-
tion, 50; action in plant feeding, 58;
amoimt needed for given crop, 87;
least amount forp.aj'ingerop,95; least
amount in soil which permits growth,
111, 225; retained by sand, 114, 224;
insufl5ciency for irrigation, 117; in
siibsoiled ground, 136; lost through
mulches, 142, 201 ; lost from wet soil,
148; in fallow ground, 1,55, 225; capil-
lary spreading, 161, 330, 377; conserved
by tillage, 164, 353 ; importance of
amo\int and distribution in potato
culture, 172; duty, 196 (see Duty of
water) ; amount for single irrigation
222, 223, 225, 227, 234 ; capacity of soils
224, 353; best amount for crops, 227
measurement, 239; cold, for irriga
tion, 249; value of turbid, for irriga
tion, 259; alkaU waters, 267, 268, 284
285, 287; supplying, for irrigation, 290
methods of applying, 329 ; loss by per
eolation, 330; rate of application, 331
332, 337 ; depth in flooding, 346
amount needed for lawns and parks
392 ; amount needed for sub-irriga
tion, 397, 401.
Water level, 416.
Water-logged soil, 11, 334.
Water-meadows, 16, 92, 219, 251, 359 ;
English, 76, 360; use of sewage, 220,
254, 403, 409; frequency of u-rigation,
237; Belgian, 362; Italian, 362; moun-
tain, 74, 365.
Water supply, for irrigation wells, 78,
84, 85, 86, 251, 393 ; from rivers, 290;
undergi-ound waters, 304; lifting by
water-power, 306 ; storm water, 311 ;
by wind power, 312; by engines, 324,
326; cost, 324; by animal power, 325,
328; for cranberries, 367.
Water wheels, 75, 306, 308.
Weiss, number of breathing pores, 51.
Wells, for ii-rigation, 78, 84, 2.51, 393; in
Algeria, 85; in Hawaii, 86; for lawns
and gardens, 393.
Wheat, ratio of grain to straw, 96;
water used, 97, 101, 215; intertillage,
158; frequency of irrigation, 235.
Willcocks,-W., Egyptian irrigation, 84,
r 211; cost of pumping, 326.
Wilson, H. M., area of land irrigated,
88; duty of water, 211; lifting water,
309, 311, 325, 327.
Winds, lessening desti'uctive effects,
168.
Windbreaks, 169.
502
Index
Windmills, conditions for highest ser-
vice, 318; for lifting water, 312, 316,
318, 367; capacity for irrigation, 318;
use in drainage, 463.
Wind power, for irrigation, 312; work
done by months, 315; work done by
10-day periods, 316.
Wolff, A. R., 318.
The Best and Newest
Rural Books
Two. series of books on leading topics con-
nected with agricultural and rural life are here
mentioned. Each book is the work of a
specialist, under the editorial supervision of Pro-
fessor L. H. Bailey, of the Cornell University, and
is readable, clear-cut and practical.
THE RURAL SCIENCE SERIES
Includes books which state the underlying principles of agri-
culture in plain language. They are suitable for consultation
alike by the amateur or professional tiller of the soil, the
scientist or the student, and are freely illustrated and finely
made.
The following volumes are now ready:
THE SOIL. By F. H. King, of the University of Wisconsin. 303 pp. 75 cts.
THE FERTILITY OF THE LAND. By I. P. Roberts, of Cornell Univer-
sity. 440 pp. $1.25.
THE SPRAYING OF PLANTS. By E. G. Lodeman, late of Cornell Uni-
versity. 399 pp. $1.
MILK AND ITS PRODUCTS. By H. H. Wing, of Cornell University.
. 280 pp. $1.
THE PRINCIPLES OF FRUIT-GROWING. By L. H. Bailey. 520 pp. $1.25.
BUSH FRUITS. By F. W, Card, of Rhode Island College of Agriculture
and Mechanic Arts. 549 pp. $1.50.
FERTILIZERS. By E. B. Voorhees, of New Jersey Experiment Station*
335 pp. $1.
IRRIGATION AND DRAINAGE. By F. H. KixG, University of Wisconsin.
500 pp. $1.50.
New volumes will be added from time to time to the
EuRAL Science Series. The following are in preparation:
PHYSIOLOGY OF PLANTS. By J. 0. Arthur, Purdue University.
PRINCIPLES OF BREEDING OF ANIMALS. By W. H. Brewer, of
Yale University.
PLANT PATHOLOGY. By B. T. Galloway and associates of U. S. Depart-
ment of Agriculture.
SEEDS AND SEED-GROWING. By G. H. HiCKS, of U. S. Dept. of Agi-.
LEGUMINOUS PLANTS AND NITROGEN-GATHERING. By E. W.
Hilgard, of LTniversity of California.
FEEDING OP ANIMALS. By W. H. Jordan, of New York State Experi-
ment Station.
RURAL WEALTH AND WELFARE. By GeORGE T. Fairchild, Ex-Presi-
dent of tlie Agricultural College of Kansas.
FARM POULTRY. By George C. Watson, of Pennsylvania State College.
T
THE RURAL SCIENCE SERIES
HE SOIL. Its Nature, Relations and
Fundamental Principles of Management.
By F. H. KING, Professor of Agricultural Physics
in the University of Wisconsin.
303 PACES — 45 ILLUSTRATIONS — 75 CENTS
A luminous and practical discussion of the soil
and its various attributes. As an understanding of
the soil in some measure is of vital necessity to
success in even the most limited agricultural opera-
tions, the importance of a work like this cannot
easily be overestimated. The progressive farmer will
be greatly helped by a thoughtful perusal of this
unique book, which has received the warmest appro-
bation of teachers and farmers in all parts of the
country.
The Soil comprises an introduction, which discusses the mak-
ing of soils by natural agencies; and chapters follow on the nature,
functions, origin and wasting of soils; texture, composition and
kinds of soils; nitrogen of the soil; capillarity, solution, diffusion,
and osmosis; soil water; conservation of soil moisture; distribu-
tion of roots in the soil; soil temperature; relations of air to the
soil; farm drainage; irrigation; physical effects of tillage and
fertilizers.
"I consider it a most desirable addition to our agricultural literature,
and a distinct advance over previous treatises on the same subject, jiot
anly for popular use, but also for students and specialists, who will find
many new and useful suggestions therein."
E. W. HiLGARD,
Director of Agriculttiral Experiment Station.
Berkeley, Cal.
"It is a book wliioh progressive farmei's will come to regard as one
of the essential implements of farm hie."— Boston Daily Advertiser.
"The manual is brief, accurate, comprehensive, and hits the practical
point every time." — Independent.
T
THE RURAL SCIENCE SERIES
HE FERTILITY OF THE LAND: A
Summary Sketch of the Relationship of
Farm-Practice to the Maintaining and In-
creasing of the Productivity of the Soil.
By I. P ROBERTS, Director of the College of Agri-
culture, Cornell University.
SECOND EDITION— 432 PACES-45 ILLUSTRATIONS— S 1 .25
This -work, written by one vrho has been termed
"the wisest farmer iu America," takes up the treat-
ment of the soil from the standpoint of the farmer
rather than that of the scientist. It embodies the
results of years of careful experimentation and obser-
vation along practical lines, and will be found help-
ful and inspiring to a marked degree. Xo other one
book could be so heartily recommeuded to the pro-
gressive farmer, on subjects of vital interest to him,
as this fresh and interesting series of talks — for Pro-
fessor Roberts seems to be personally addressing the
reader.
The FERTiLiTr of the Land iucludes A Chat with the Young
Farmer ; Inventory of the Laud ; Evolution of the Plow (fully illus-
trated); The Means and Philosophy of Tilling the Land (telling how
and why we should plow, harrow, etc.) ; Conserving Moisture ; Irri-
gation and Drainage ; Manures (in four unique, illustrated chap-
ters); Nitrogen; Potash and Phosphoric Acid; Lime and other
dressings ; Commercial Fertilizers ; The Use of Clovers, Fallows
and Rotations ; Appendix.
"In short, the book will be found helpful to the farmer, in that it will
en.ible him to go through the routine of his everyday work with intelli-
gence, and, therefore, with skill .and tlie (issurauce of wider success."—
Garden and Forest.
T
THE RURAL SCIENCE SERIES
HE SPRAYING OF PLANTS: a
Succinct Account of the History, Principles
and Practice of the Application of Liquids
and Powders to Plants for the Purpose of
Destroying Insects and Fungi. By E. G.
LODEMAN, late Instructor in Horticulture in the
Cornell Universit\'.
399 PACES— 92 ILLUSTRATIONS— S 1 .00
In these days this subject is conceded to be of
especial importance to the horticulturist; for it is
only by intelligent spraying that many large fruit
interests are saved from utter extinction. Professor
Lodeman treats the subject both historically and
practically, and the work forms the only complete
manual of spraying, being admittedly the standard
authority. Xot only is spraying discussed in its
relations to the plant or tree and the crop, but the
diseases and insects which are to be combatted are
most fully presented.
The Spratixg of Pla>t.s includes in its first part a complete
history of the rise of spraying, both in this country and abroad.
There are also full illustrated accounts of pumps and nozzles, com-
plete recipes of formulas, and the like. The second part, compris-
ing 135 pages, entitled "Specific Directions for Spraying Cultivated
Plants,"' is an alphabetical illustrated account of the various insects
and fungi, vrith methods of treating them.
"Mr. Lodeman has gathered the resnlts of an immense amotint of
experiments, both in Europe and America, and his book can be trusted not
only as a manual of practice, but as a true and well classified record of our
knowledge on this subject at the present time." — Garden and Forest.
"There is nothing else on the subject so new, complete, accurate and
available."— irenuig Post (.X.V.).
M
THE RURAL SCIENCE SERIES
ILK AND ITS PRODUCTS: A
Treatise upon the Nature and Qualities of
Dairy Milk, and the Manufacture of But-
ter and Cheese. By HENRY H. WING, Assis-
tant Professor of Dairy Husbandry in the Cornell
University.
208 PACES— 33 ILLUSTRATIONS— 3 1 .00
In this volume the whole field of dairying is in-
telligently considered. The production and charac-
ter of the lacteal fluid are first discussed, and then
in order are taken up the marketing of milk, the
production and handling of butter, cheese, and all
the products of the dairy. Although the book is
up to date in its science, it is none the less a com-
plete guide to modern dairy practice. The illustra-
tions serve to point the practical recommendations
of the text. No recent work on dairying has been
so well received as this.
Milk and Its Products includes chapters on: Secretion of
Milk ; Composition of Milk ; Testing of Milk ; Ferments and Fer-
mentations of Milk, and their Control ; Market Milk ; Separation of
Cream ; Ripening of Cream ; Churning ; Finishing and Marketing
Butter; Milk for Cheese-Making; Cheddar Cheese-Making; Varie-
ties of Cheese; By-Products of the Dairy; Butter and Cheese Fac-
tories; Statistics and Economics of the Dairy Industry; Appendix,
comprising useful rules and tests, metric system, dairy laws, and
references to dairy literature.
"The book is a mine of valuable information, and ought to be in the
hands of all progressive dairymen."— TVew England Farmer.
THE RURAL SCIENCE SERIES
T
HE PRINCIPLES OF FRUIT-
GROWING. By L. H. BAILEY, Professor of
Horticulture in the Cornell University.
520 PACES— 114 ILLUSTRATIONS— SI. 26
There have been manuals and treatises on fruit-
growing, but this volume is the first consistent
presentation of the underlying principles affecting
the growth of the various fruits. It is thus unique,
and it occupies a field of the greatest importance.
It joins science and practice, for it not only discusses
the reasons for certain operations, but presents the
most approved methods, gathered from the successful
fruit-growers of America. It appeals especially to
the horticulturist who is willing to have his brain
direct and supplement the work of his hands, and to
acquire a knowledge of principles rather than a mere
memorandum of their application.
The Principles of Fkuit-Growixg includes: Introductory
Discussion, comprising an inventory and classification of fruits, the
fruit zones, the outlook for fruit-growing; the Location and its
Climate, -with a full discussion of frosts; the Tilling of Fruit
Lands; the Fertilizing of Fruit Lands; the Planting of Orchards;
Secondary Care of Orchards ; Diseases, Insects and Spraying ;
Picking and Packing aud Storing Fruits, Shipping, etc.; and a
bibliography of American writings on the subject.
"The book is very practical in its treatment of the snbjeet of fruit-
growing, after a brief introductory entering at once into the discussion of
the location of tlie orchard, following that with the tillage of fruit lands,
dealing with the planting and care of fruits. Taken all in all, it is the most
complete book on fruit-growing at a small price we have seen." — Western
Rural.
B
THE RURAL SCIENCE SERIES
USH-FRUITS : A Horticultural Mono-
graph of Raspberries, Blackberries, Dew-
berries, Currants, Gooseberries, and other
Shrub-like Fruits. By FRED W. card, Pro-
fessor of Horticulture in the Rhode Island College of
Agriculture and Mechanic Arts, and Horticulturist to
the Experiment Station.
549 PACES— 113 ILLUSTRATIONS — $ 1 .50
The great importance in this country of the fruits
mentioned in the title justifies their treatment in a sep-
arate monograph. Professor Card, with a lifelong
training as a grower of these fruits, as well as years
of studj^ as experimenter and teacher, takes up the
subject with special fitness. Not only are tlie fruits
treated with respect to culture, varieties, histor}', etc.,
bnt the diseases and the insects which attack them
are fully discussed. There are numerous illnstrations,
and the volume is an important contribution to the
literature of fruit-growing.
Bush-Fruits includes in Part I An Introduetorj' Discussion
(Location, fi'ertilizers, Planting and Management, Pruning, Winter-
killing, Propagation, Thinning, Effect of Spraying on Po.lination,
Forcing, Picking, Packages and Marketing).
Part II treats of the Brambles; Red Raspberries (Soil, Locution,
Fertilizing, Propagation, etc.. Autumn Fruiting, Marketing, Duration,
Hardiness, Yields, Normal Profits); Black Raspberries (Soil, etc..
Harvesting, Drjing. Marketing, the Evaporated Raspberry Industry.
Usual Profits); Blackberries (Soil, etc.. Marketing, etc.); Dewberries
(Soil, etc.. Marketing, etc.); Miscellaneous Brambles (Maj'berry,
Strawberrj'-Raspberry, Wineberrj-, Chinese Raspberry, Ornamental
Species); Varieties of Raspberries; Varieties of Blackberries and
Dewberries; Yields; Insects; Diseases; Botany.
Part III discusses the Groselles ; Currants ( Soil, Fertilizers, Propa-
gation, Planting, Tillatje, Pruning, Gathering and Marketing, Uses,
Duration, Hardiness, Yield, Profits); Gooseberries (Soil, etc., Hardi-
ness, Profits); Varieties of Currants; Varieties of Gooseberries;
Injurious Insects; Diseases; Botany.
Part IV treats Miscellaneous Types, including other Species of
Bush-Pruits (Buffalo Berry, The Goumi, Huckleberries, Juneber-
ries, Tree Cranberry, Barberry, Sand Cherry) ; Appendix.
THE RURAL SCIENCE SERIES
FERTILIZERS: The Source, Character and
Composition of Natural, Home-made and
Manufactured Fertilizers; and Suggestions
as to Their Use for Different Crops and
Conditions. By EDWARD B. VOORHEES,
Director of the New Jersey Experiment Station,
and Professor of Agriculture in Rutgers College.
335 PACES ~S I. CO
This book discusses the difficult questions of fer-
tilizers in such plain and untechnical language that
those who are wholly unlearned in chemistry can
use it. There are no elaborate tables. The book
instructs upon the fundamental principles of the use
of fertilizers, so that the farmer is able, when he
reads it, to determine for himself what his practice
shall be. It is not an advocate for commercial fer-
tilizers, but tells simply and directly what the truth
is respecting their value. It explains the latest
results of experiments to determine what fertilizers
are best for given soils and given crops.
Fertilizers includes the following : The Natural Fer-
tility of the Soil, and Sources of Loss of the Elements of
Fertility; The Function of Manures and Fertilizers, and the
Need of Artificial Fertilizers; Nitrogenous Fertilizers; Phos-
phates; Superphosphates and Potash; Miscellaneous Fertiliz-
ing Materials ; Purchase of Fertilizers ; Chemical Analyses of
Fertilizers ; Methods of Use of Fertilizers ; Fertilizers for
Cereals and Grasses, Potatoes, Sweet Potatoes, Tomatoes and
Sugar Beets ; Green Forage Crops ; Market-garden Crops ;
Orchard Fruits and Berries ; Fertilizers for various special
crops.
T
WORKS BY PROFESSOR BAILEY
HE PRINCIPLES OF AGRICUL-
TURE: A Text-Book for Schools and
Rural Societies. Edited by L. H. bailey,
with contributions from his Colleagues in the
Cornell University.
300 PACES— 92 ILLUSTRATIONS — SI .25
This is an attempt to analyze the complex sub-
ject of agriculture, and to present the underlying
principles and factors in clear, terse English. Each
chapter is in two parts : the first part, or the
principles, is in numbered paragraphs in very large
type (the size used in "Lessons with Plants"); the
second part contains informal suggestions to the
teacher and pupil, with illustrations. It is one of
the few attempts to coordinate all the various agri-
cultural subjects, showing the relative importance
and position of each. It is a skeleton of agri-
cultural science and practice. Full references are
made to such literature as the teacher or pupil may
be able to secure.
The Principles of Agriculture comprises the following
subjects : Introduction, discussing what agriculture is. Part I,
The Soil, containing : The Contents of the Soil ; The Texture of
the Soil ; The Moisture in the Soil ; The Tillage of the Soil ;
Enriching the Soil by Farm Resources ; Enriching the Soil by
Commercial Resources. Part II, The Plant and the Crop, com-
prising : The Offices of the Plant ; How the Plant Lives ; The
Propagation of the Plant ; Preparation of the Land for the Seed ;
Subsequent Care of the Plant ; Pastures, Meadows, and Forage.
Part III, The Animal and Stock, comprising : The Offices of the
Animal ; How the Animal LiA'es ; The Feeding of the Animal; The
Breeding of the Animal ; Management of Stock.
L
WORKS BY PROFESSOR BAILEY
ESSONS WITH PLANTS: Sugges-
tions for Seeing and Interpreting Some of
the Common Forms of Vegetation. By l.
H. BAILEY, Professor of Horticulture in the Cornell
Universit\', with delineations from nature by W. S.
HOLDSWORTH, of the University' of Michigan.
523 PACES— 443 ILLUSTRATIONS— 3 1 . 1
While thi.s volume does not ask attention as a
manual of liotauy, it is, iu effeet, a most admirable
text-book on that science, though free from the
tedious technical terms which usually characterize
manuals on the sciences. The motive of the book
is the cultivation of the power of observation and
the ability to draw proper inferences therefrom It
is pure "nature study" that it inculcates, and the
charm of its manner and method will be felt by even
a casual reader. The numerous beautiful illus-
trations, whicli greatly aid the reader in his com-
prehension of the truths presented, are a marked
feature of the work.
Lessons with Plants is admirably adapted to class use in
high schools and academies. It includes Studies of Twigs and
Buds ; Studies of Leaves and Foliage ; Studies of Flowers ;
Studies of the Fructification ; Studies of the Propagation of
Plants; Studies of the Behavior and Habits of Plants; Studies of
the Kinds of Plants; Suggestions and Reviews; Glossary.
:iRST LESSONS WITH PLANTS. An abridge-
ruent of above. 127 pages, 116 illustrations, 40 cents net.
THE MACMILLAN COMPANY,
66 Fifth Avenue. NFW YORK-